diff --git a/test/test_datasets_utils.py b/test/test_datasets_utils.py
index 7fceb5f25e6..1940c9e8493 100644
--- a/test/test_datasets_utils.py
+++ b/test/test_datasets_utils.py
@@ -107,6 +107,11 @@ def test_extract_gzip(self):
                     data = nf.read()
                 self.assertEqual(data, 'this is the content')
 
+    def test_verify_str_arg(self):
+        self.assertEqual("a", utils.verify_str_arg("a", "arg", ("a",)))
+        self.assertRaises(ValueError, utils.verify_str_arg, 0, ("a",), "arg")
+        self.assertRaises(ValueError, utils.verify_str_arg, "b", ("a",), "arg")
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/torchvision/datasets/caltech.py b/torchvision/datasets/caltech.py
index 6c14500f4f3..e18349d76a0 100644
--- a/torchvision/datasets/caltech.py
+++ b/torchvision/datasets/caltech.py
@@ -4,7 +4,7 @@
 import os.path
 
 from .vision import VisionDataset
-from .utils import download_and_extract_archive, makedir_exist_ok
+from .utils import download_and_extract_archive, makedir_exist_ok, verify_str_arg
 
 
 class Caltech101(VisionDataset):
@@ -32,10 +32,10 @@ def __init__(self, root, target_type="category", transform=None,
                                          transform=transform,
                                          target_transform=target_transform)
         makedir_exist_ok(self.root)
-        if isinstance(target_type, list):
-            self.target_type = target_type
-        else:
-            self.target_type = [target_type]
+        if not isinstance(target_type, list):
+            target_type = [target_type]
+        self.target_type = [verify_str_arg(t, "target_type", ("category", "annotation"))
+                            for t in target_type]
 
         if download:
             self.download()
@@ -88,8 +88,6 @@ def __getitem__(self, index):
                                                      self.annotation_categories[self.y[index]],
                                                      "annotation_{:04d}.mat".format(self.index[index])))
                 target.append(data["obj_contour"])
-            else:
-                raise ValueError("Target type \"{}\" is not recognized.".format(t))
         target = tuple(target) if len(target) > 1 else target[0]
 
         if self.transform is not None:
diff --git a/torchvision/datasets/celeba.py b/torchvision/datasets/celeba.py
index 88033f3f375..8d593218e46 100644
--- a/torchvision/datasets/celeba.py
+++ b/torchvision/datasets/celeba.py
@@ -3,7 +3,7 @@
 import os
 import PIL
 from .vision import VisionDataset
-from .utils import download_file_from_google_drive, check_integrity
+from .utils import download_file_from_google_drive, check_integrity, verify_str_arg
 
 
 class CelebA(VisionDataset):
@@ -66,17 +66,14 @@ def __init__(self, root, split="train", target_type="attr", transform=None,
             raise RuntimeError('Dataset not found or corrupted.' +
                                ' You can use download=True to download it')
 
-        if split.lower() == "train":
-            split = 0
-        elif split.lower() == "valid":
-            split = 1
-        elif split.lower() == "test":
-            split = 2
-        elif split.lower() == "all":
-            split = None
-        else:
-            raise ValueError('Wrong split entered! Please use "train", '
-                             '"valid", "test", or "all"')
+        split_map = {
+            "train": 0,
+            "valid": 1,
+            "test": 2,
+            "all": None,
+        }
+        split = split_map[verify_str_arg(split.lower(), "split",
+                                         ("train", "valid", "test", "all"))]
 
         fn = partial(os.path.join, self.root, self.base_folder)
         splits = pandas.read_csv(fn("list_eval_partition.txt"), delim_whitespace=True, header=None, index_col=0)
@@ -134,6 +131,7 @@ def __getitem__(self, index):
             elif t == "landmarks":
                 target.append(self.landmarks_align[index, :])
             else:
+                # TODO: refactor with utils.verify_str_arg
                 raise ValueError("Target type \"{}\" is not recognized.".format(t))
         target = tuple(target) if len(target) > 1 else target[0]
 
diff --git a/torchvision/datasets/cityscapes.py b/torchvision/datasets/cityscapes.py
index cfa7f0043b3..56ff20bc3f1 100644
--- a/torchvision/datasets/cityscapes.py
+++ b/torchvision/datasets/cityscapes.py
@@ -3,7 +3,7 @@
 from collections import namedtuple
 import zipfile
 
-from .utils import extract_archive
+from .utils import extract_archive, verify_str_arg, iterable_to_str
 from .vision import VisionDataset
 from PIL import Image
 
@@ -109,22 +109,21 @@ def __init__(self, root, split='train', mode='fine', target_type='instance',
         self.images = []
         self.targets = []
 
-        if mode not in ['fine', 'coarse']:
-            raise ValueError('Invalid mode! Please use mode="fine" or mode="coarse"')
-
-        if mode == 'fine' and split not in ['train', 'test', 'val']:
-            raise ValueError('Invalid split for mode "fine"! Please use split="train", split="test"'
-                             ' or split="val"')
-        elif mode == 'coarse' and split not in ['train', 'train_extra', 'val']:
-            raise ValueError('Invalid split for mode "coarse"! Please use split="train", split="train_extra"'
-                             ' or split="val"')
+        verify_str_arg(mode, "mode", ("fine", "coarse"))
+        if mode == "fine":
+            valid_modes = ("train", "test", "val")
+        else:
+            valid_modes = ("train", "train_extra", "val")
+        msg = ("Unknown value '{}' for argument split if mode is '{}'. "
+               "Valid values are {{{}}}.")
+        msg = msg.format(split, mode, iterable_to_str(valid_modes))
+        verify_str_arg(split, "split", valid_modes, msg)
 
         if not isinstance(target_type, list):
             self.target_type = [target_type]
-
-        if not all(t in ['instance', 'semantic', 'polygon', 'color'] for t in self.target_type):
-            raise ValueError('Invalid value for "target_type"! Valid values are: "instance", "semantic", "polygon"'
-                             ' or "color"')
+        [verify_str_arg(value, "target_type",
+                        ("instance", "semantic", "polygon", "color"))
+         for value in self.target_type]
 
         if not os.path.isdir(self.images_dir) or not os.path.isdir(self.targets_dir):
 
diff --git a/torchvision/datasets/imagenet.py b/torchvision/datasets/imagenet.py
index d6eead13a35..14a256c66ab 100644
--- a/torchvision/datasets/imagenet.py
+++ b/torchvision/datasets/imagenet.py
@@ -4,7 +4,8 @@
 import tempfile
 import torch
 from .folder import ImageFolder
-from .utils import check_integrity, download_and_extract_archive, extract_archive
+from .utils import check_integrity, download_and_extract_archive, extract_archive, \
+    verify_str_arg
 
 ARCHIVE_DICT = {
     'train': {
@@ -48,7 +49,7 @@ class ImageNet(ImageFolder):
 
     def __init__(self, root, split='train', download=False, **kwargs):
         root = self.root = os.path.expanduser(root)
-        self.split = self._verify_split(split)
+        self.split = verify_str_arg(split, "split", ("train", "val"))
 
         if download:
             self.download()
@@ -109,17 +110,6 @@ def _load_meta_file(self):
     def _save_meta_file(self, wnid_to_class, val_wnids):
         torch.save((wnid_to_class, val_wnids), self.meta_file)
 
-    def _verify_split(self, split):
-        if split not in self.valid_splits:
-            msg = "Unknown split {} .".format(split)
-            msg += "Valid splits are {{}}.".format(", ".join(self.valid_splits))
-            raise ValueError(msg)
-        return split
-
-    @property
-    def valid_splits(self):
-        return 'train', 'val'
-
     @property
     def split_folder(self):
         return os.path.join(self.root, self.split)
diff --git a/torchvision/datasets/lsun.py b/torchvision/datasets/lsun.py
index aec65722cd9..66234a35aeb 100644
--- a/torchvision/datasets/lsun.py
+++ b/torchvision/datasets/lsun.py
@@ -11,6 +11,8 @@
 else:
     import pickle
 
+from .utils import verify_str_arg, iterable_to_str
+
 
 class LSUNClass(VisionDataset):
     def __init__(self, root, transform=None, target_transform=None):
@@ -75,27 +77,31 @@ def __init__(self, root, classes='train', transform=None, target_transform=None)
                       'living_room', 'restaurant', 'tower']
         dset_opts = ['train', 'val', 'test']
 
-        if type(classes) == str and classes in dset_opts:
+        try:
+            verify_str_arg(classes, "classes", dset_opts)
             if classes == 'test':
                 classes = [classes]
             else:
                 classes = [c + '_' + classes for c in categories]
-        elif type(classes) == list:
+        except ValueError:
+            # TODO: Should this check for Iterable instead of list?
+            if not isinstance(classes, list):
+                raise ValueError
             for c in classes:
+                # TODO: This assumes each item is a str (or subclass). Should this
+                #   also be checked?
                 c_short = c.split('_')
-                c_short.pop(len(c_short) - 1)
-                c_short = '_'.join(c_short)
-                if c_short not in categories:
-                    raise (ValueError('Unknown LSUN class: ' + c_short + '.'
-                                      'Options are: ' + str(categories)))
-                c_short = c.split('_')
-                c_short = c_short.pop(len(c_short) - 1)
-                if c_short not in dset_opts:
-                    raise (ValueError('Unknown postfix: ' + c_short + '.'
-                                      'Options are: ' + str(dset_opts)))
-        else:
-            raise (ValueError('Unknown option for classes'))
-        self.classes = classes
+                category, dset_opt = '_'.join(c_short[:-1]), c_short[-1]
+                msg_fmtstr = "Unknown value '{}' for {}. Valid values are {{{}}}."
+
+                msg = msg_fmtstr.format(category, "LSUN class",
+                                        iterable_to_str(categories))
+                verify_str_arg(category, valid_values=categories, custom_msg=msg)
+
+                msg = msg_fmtstr.format(dset_opt, "postfix", iterable_to_str(dset_opts))
+                verify_str_arg(dset_opt, valid_values=dset_opts, custom_msg=msg)
+        finally:
+            self.classes = classes
 
         # for each class, create an LSUNClassDataset
         self.dbs = []
diff --git a/torchvision/datasets/mnist.py b/torchvision/datasets/mnist.py
index 4847cfdcaa9..2109decff33 100644
--- a/torchvision/datasets/mnist.py
+++ b/torchvision/datasets/mnist.py
@@ -7,7 +7,8 @@
 import numpy as np
 import torch
 import codecs
-from .utils import download_url, download_and_extract_archive, extract_archive, makedir_exist_ok
+from .utils import download_url, download_and_extract_archive, extract_archive, \
+    makedir_exist_ok, verify_str_arg
 
 
 class MNIST(VisionDataset):
@@ -230,11 +231,7 @@ class EMNIST(MNIST):
     splits = ('byclass', 'bymerge', 'balanced', 'letters', 'digits', 'mnist')
 
     def __init__(self, root, split, **kwargs):
-        if split not in self.splits:
-            raise ValueError('Split "{}" not found. Valid splits are: {}'.format(
-                split, ', '.join(self.splits),
-            ))
-        self.split = split
+        self.split = verify_str_arg(split, "split", self.splits)
         self.training_file = self._training_file(split)
         self.test_file = self._test_file(split)
         super(EMNIST, self).__init__(root, **kwargs)
@@ -336,10 +333,7 @@ class QMNIST(MNIST):
     def __init__(self, root, what=None, compat=True, train=True, **kwargs):
         if what is None:
             what = 'train' if train else 'test'
-        if not self.subsets.get(what):
-            raise RuntimeError("Argument 'what' should be one of: \n  " +
-                               repr(tuple(self.subsets.keys())))
-        self.what = what
+        self.what = verify_str_arg(what, "what", tuple(self.subsets.keys()))
         self.compat = compat
         self.data_file = what + '.pt'
         self.training_file = self.data_file
diff --git a/torchvision/datasets/sbd.py b/torchvision/datasets/sbd.py
index 3c9202fdbfd..c4713f72576 100644
--- a/torchvision/datasets/sbd.py
+++ b/torchvision/datasets/sbd.py
@@ -5,7 +5,7 @@
 import numpy as np
 
 from PIL import Image
-from .utils import download_url
+from .utils import download_url, verify_str_arg
 from .voc import download_extract
 
 
@@ -64,12 +64,9 @@ def __init__(self,
                                "pip install scipy")
 
         super(SBDataset, self).__init__(root, transforms)
-
-        if mode not in ("segmentation", "boundaries"):
-            raise ValueError("Argument mode should be 'segmentation' or 'boundaries'")
-
-        self.image_set = image_set
-        self.mode = mode
+        self.image_set = verify_str_arg(image_set, "image_set",
+                                        ("train", "val", "train_noval"))
+        self.mode = verify_str_arg(mode, "mode", ("segmentation", "boundaries"))
         self.num_classes = 20
 
         sbd_root = self.root
@@ -91,11 +88,6 @@ def __init__(self,
 
         split_f = os.path.join(sbd_root, image_set.rstrip('\n') + '.txt')
 
-        if not os.path.exists(split_f):
-            raise ValueError(
-                'Wrong image_set entered! Please use image_set="train" '
-                'or image_set="val" or image_set="train_noval"')
-
         with open(os.path.join(split_f), "r") as f:
             file_names = [x.strip() for x in f.readlines()]
 
diff --git a/torchvision/datasets/stl10.py b/torchvision/datasets/stl10.py
index 7c49877bfcc..863dbf0fbf4 100644
--- a/torchvision/datasets/stl10.py
+++ b/torchvision/datasets/stl10.py
@@ -5,7 +5,7 @@
 import numpy as np
 
 from .vision import VisionDataset
-from .utils import check_integrity, download_and_extract_archive
+from .utils import check_integrity, download_and_extract_archive, verify_str_arg
 
 
 class STL10(VisionDataset):
@@ -48,13 +48,9 @@ class STL10(VisionDataset):
 
     def __init__(self, root, split='train', folds=None, transform=None,
                  target_transform=None, download=False):
-        if split not in self.splits:
-            raise ValueError('Split "{}" not found. Valid splits are: {}'.format(
-                split, ', '.join(self.splits),
-            ))
         super(STL10, self).__init__(root, transform=transform,
                                     target_transform=target_transform)
-        self.split = split  # train/test/unlabeled set
+        self.split = verify_str_arg(split, "split", self.splits)
         self.folds = folds  # one of the 10 pre-defined folds or the full dataset
 
         if download:
@@ -167,4 +163,6 @@ def __load_folds(self, folds):
                     list_idx = np.fromstring(str_idx, dtype=np.uint8, sep=' ')
                     self.data, self.labels = self.data[list_idx, :, :, :], self.labels[list_idx]
             else:
+                # FIXME: docstring allows None for folds (it is even the default value)
+                #  Is this intended?
                 raise ValueError('Folds "{}" not found. Valid splits are: 0-9.'.format(folds))
diff --git a/torchvision/datasets/svhn.py b/torchvision/datasets/svhn.py
index 0ceb1099843..4d8ed990bdb 100644
--- a/torchvision/datasets/svhn.py
+++ b/torchvision/datasets/svhn.py
@@ -4,7 +4,7 @@
 import os
 import os.path
 import numpy as np
-from .utils import download_url, check_integrity
+from .utils import download_url, check_integrity, verify_str_arg
 
 
 class SVHN(VisionDataset):
@@ -43,12 +43,7 @@ def __init__(self, root, split='train', transform=None, target_transform=None,
                  download=False):
         super(SVHN, self).__init__(root, transform=transform,
                                    target_transform=target_transform)
-        self.split = split  # training set or test set or extra set
-
-        if self.split not in self.split_list:
-            raise ValueError('Wrong split entered! Please use split="train" '
-                             'or split="extra" or split="test"')
-
+        self.split = verify_str_arg(split, "split", tuple(self.split_list.keys()))
         self.url = self.split_list[split][0]
         self.filename = self.split_list[split][1]
         self.file_md5 = self.split_list[split][2]
diff --git a/torchvision/datasets/utils.py b/torchvision/datasets/utils.py
index 27315e6e912..937bed90399 100644
--- a/torchvision/datasets/utils.py
+++ b/torchvision/datasets/utils.py
@@ -6,6 +6,7 @@
 import tarfile
 import zipfile
 
+import torch
 from torch.utils.model_zoo import tqdm
 
 
@@ -249,3 +250,32 @@ def download_and_extract_archive(url, download_root, extract_root=None, filename
     archive = os.path.join(download_root, filename)
     print("Extracting {} to {}".format(archive, extract_root))
     extract_archive(archive, extract_root, remove_finished)
+
+
+def iterable_to_str(iterable):
+    return "'" + "', '".join([str(item) for item in iterable]) + "'"
+
+
+def verify_str_arg(value, arg=None, valid_values=None, custom_msg=None):
+    if not isinstance(value, torch._six.string_classes):
+        if arg is None:
+            msg = "Expected type str, but got type {type}."
+        else:
+            msg = "Expected type str for argument {arg}, but got type {type}."
+        msg = msg.format(type=type(value), arg=arg)
+        raise ValueError(msg)
+
+    if valid_values is None:
+        return value
+
+    if value not in valid_values:
+        if custom_msg is not None:
+            msg = custom_msg
+        else:
+            msg = ("Unknown value '{value}' for argument {arg}. "
+                   "Valid values are {{{valid_values}}}.")
+            msg = msg.format(value=value, arg=arg,
+                             valid_values=iterable_to_str(valid_values))
+        raise ValueError(msg)
+
+    return value
diff --git a/torchvision/datasets/voc.py b/torchvision/datasets/voc.py
index 390c441911d..8a6925011ba 100644
--- a/torchvision/datasets/voc.py
+++ b/torchvision/datasets/voc.py
@@ -10,7 +10,7 @@
     import xml.etree.ElementTree as ET
 
 from PIL import Image
-from .utils import download_url, check_integrity
+from .utils import download_url, check_integrity, verify_str_arg
 
 DATASET_YEAR_DICT = {
     '2012': {
@@ -83,7 +83,8 @@ def __init__(self,
         self.url = DATASET_YEAR_DICT[year]['url']
         self.filename = DATASET_YEAR_DICT[year]['filename']
         self.md5 = DATASET_YEAR_DICT[year]['md5']
-        self.image_set = image_set
+        self.image_set = verify_str_arg(image_set, "image_set",
+                                        ("train", "trainval", "val"))
         base_dir = DATASET_YEAR_DICT[year]['base_dir']
         voc_root = os.path.join(self.root, base_dir)
         image_dir = os.path.join(voc_root, 'JPEGImages')
@@ -100,11 +101,6 @@ def __init__(self,
 
         split_f = os.path.join(splits_dir, image_set.rstrip('\n') + '.txt')
 
-        if not os.path.exists(split_f):
-            raise ValueError(
-                'Wrong image_set entered! Please use image_set="train" '
-                'or image_set="trainval" or image_set="val"')
-
         with open(os.path.join(split_f), "r") as f:
             file_names = [x.strip() for x in f.readlines()]
 
@@ -164,7 +160,8 @@ def __init__(self,
         self.url = DATASET_YEAR_DICT[year]['url']
         self.filename = DATASET_YEAR_DICT[year]['filename']
         self.md5 = DATASET_YEAR_DICT[year]['md5']
-        self.image_set = image_set
+        self.image_set = verify_str_arg(image_set, "image_set",
+                                        ("train", "trainval", "val"))
 
         base_dir = DATASET_YEAR_DICT[year]['base_dir']
         voc_root = os.path.join(self.root, base_dir)
@@ -182,12 +179,6 @@ def __init__(self,
 
         split_f = os.path.join(splits_dir, image_set.rstrip('\n') + '.txt')
 
-        if not os.path.exists(split_f):
-            raise ValueError(
-                'Wrong image_set entered! Please use image_set="train" '
-                'or image_set="trainval" or image_set="val" or a valid'
-                'image_set from the VOC ImageSets/Main folder.')
-
         with open(os.path.join(split_f), "r") as f:
             file_names = [x.strip() for x in f.readlines()]