diff --git a/lib/numbers/create.js b/lib/numbers/create.js
new file mode 100644
index 0000000..03c0d4c
--- /dev/null
+++ b/lib/numbers/create.js
@@ -0,0 +1,7 @@
+var numbers = require('../numbers');
+var create = exports;
+
+create.Set = function(data) {
+	var s = new Set();
+  return s.add(data);
+};
\ No newline at end of file
diff --git a/lib/types/set.js b/lib/types/set.js
new file mode 100644
index 0000000..daeddc3
--- /dev/null
+++ b/lib/types/set.js
@@ -0,0 +1,354 @@
+var numbers = require('../numbers'),
+	  exports = Set;
+
+//TODO Determine where _getValid and _getValidElement can go.
+/**
+ * Get the information in a valid form according to the {Set} API.
+ *
+ * @param {Array|Number} Data or set of elements
+ * @param {Object} object to determine which test.
+ */
+function _getValid(data, obj) {
+  if (Set.prototype.isPrototypeOf(obj)) {
+    if (Object.prototype.toString.call(data) === '[object Array]') {
+      return data; //TODO map getValidElement.
+    } else {
+      return [data];
+    }
+  } 
+  else {
+    throw new Error(obj.constructor + " is currently not supported in _getValid.");
+  }
+}
+
+/**
+ * Get the elements in a valid form according to the {Set} API.
+ *
+ * @param {Array|Number} Element
+ * @param {Object} object to determine which test.
+ */
+function _getValidElement(d, obj) {
+  if (Set.prototype.isPrototypeOf(obj)) {
+    // currently only support numbers
+    // If hashing is implemented, it should be hashed here and rehashed in toArray
+    if (d % 1 === 0) return ''+d;
+    else throw new Error(d + " is not a valid element for a Set");
+  } 
+  else {
+    throw new Error(obj.constructor + " is currently not supported in _getValidElement.");
+  }
+}
+
+/**
+ * Core Data Structure for use in numbers.js library.
+ * This data structure implements a set (with similar API to 
+ * that of python's set data structure). 
+ *
+ * @param {Number|Array} (optional) values to add to initial Set object.
+ */
+var Set = function(data) {
+	if (arguments.length === 0) {
+    this.data = {};
+  }
+	else {
+		data = _getValid(data, this); //returns array
+    this.data = {};
+    var l = this.length,
+        i;
+    for (i = 0; i < l; i++) {
+      this.add(data[i]);
+    }
+	}
+};
+
+/**
+ * Determine if the Set has value(s).
+ *
+ * @param {Number|Array} Value(s) added to set
+ * @return {Boolean|Array} Returns a boolean array or boolean value
+ */
+Set.prototype.has = function(d) {
+  if (Object.prototype.toString.call(d) === '[object Array]') {
+    var i, 
+        l = d.length,
+        ret = [];
+    for (i = 0; i < l; i++) {
+      ret.push(this.has(d[i]));
+    }
+    return ret;  
+  }
+  else {
+    d = _getValidElement(d, this);
+    return this.data.hasOwnProperty(d);
+  }
+};
+
+/**
+ * Create a copy of the Set.
+ *
+ * @return {Set} an exact copy of this set.
+ */
+Set.prototype.clone = function() {
+  return new Set(this.toArray()); //TODO proper copy
+};
+
+/**
+ * Determine if all values in B are in this set.
+ *
+ * @param {Set|Array} Set B or array to create set from
+ * @return {Boolean} true for superset
+ */
+Set.prototype.isSuperSet = function(B) {
+  if (!Set.prototype.isPrototypeOf(B))
+    B = new Set(_getValid(B, this));
+  return this.has(B.toArray()).reduce(function(a, b) {
+    return !!a && !!b;
+  });
+};
+
+/**
+ * Determine if all values in this set are in B.
+ *
+ * @param {Set|Array} Set B or array to create set from
+ * @return {}
+ */
+Set.prototype.isSubSet = function(B) {
+  if (!Set.prototype.isPrototypeOf(B))
+    B = new Set(_getValid(B, this));
+  return B.has(this.toArray()).reduce(function(a, b) {
+    return !!a && !!b;
+  });
+};
+
+/**
+ * Convert this Set to an Array
+ *
+ * @param {Function} (optional) the function in which to sort the array by
+ * @return {Array} Array of elements in set.
+ */
+Set.prototype.toArray = function(sortFunc) {
+  var ret = Object.keys(this.data);
+  ret.map(function(a) { return +a; }); //currently supports only numbers
+  if (arguments.length === 1) ret.sort(sortFunc);
+  return ret;
+};
+
+/**
+ * Add value(s) to this Set.
+ * (A + B)
+ *
+ * @param {Number|Array} Value(s) added to set
+ * @return {Set} Updated Set
+ */
+Set.prototype.add = function(d) {
+  if (Object.prototype.toString.call(d) === '[object Array]') {
+    var i, 
+        l = d.length;
+    for (i = 0; i < l; i++) {
+      this.add(d[i]);
+    }
+  }
+  else {
+    d = _getValidElement(d, this);
+    if (!this.has(d)) {
+      this.data[d] = true;
+      this.size++;
+    }
+  }
+  return this;
+};
+
+/**
+ * Remove value(s) from this Set.
+ * (A - B)
+ *
+ * @param {Number|Array} Value(s) removed from set
+ * @return {Set} Updated Set
+ */
+Set.prototype.remove = function(d) {
+  if (Object.prototype.toString.call(d) === '[object Array]') {
+    var i, 
+        l = d.length,
+        ret = [];
+    for (i = 0; i < l; i++) {
+      ret.push(this.remove(d[i]));
+    }
+    return ret;
+  }
+  else {
+    d = _getValidElement(d, this);
+    if (this.has(d)) {
+      delete this.data[d];
+      this.size--;
+      return true;      
+    }
+    return false;
+  }
+};
+
+/**
+ * Add any elements from B that are not already in A.
+ * (A | B)
+ *
+ * @param {Set|Array} the set or data to create a set from
+ * @return {Set} Updated Set
+ */
+Set.prototype.union = function(B) {
+  if (!Set.prototype.isPrototypeOf(B))
+    B = new Set(_getValid(B, this));
+  return this.add(B.toArray());
+};
+
+/**
+ * Creates an updated set containing elements which are both in this and in B.
+ * (A & B)
+ *
+ * @param {Set|Array} the set or data to create a set from
+ * @return {Set} Updated Set
+ */
+Set.prototype.intersection = function(B) {
+  if (!Set.prototype.isPrototypeOf(B))
+    B = new Set(_getValid(B, this));
+  var BList = B.toArray(),
+      check = this.has(BList),
+      i,
+      l = BList.length,
+      commonList = [];
+  for (i = 0; i < l; i++) {
+    if (check[i])
+      commonList.push(BList[i]);
+  }
+  this = new Set(commonList);
+  return this;
+};
+
+/**
+ * Removes all elements in this set that are also in set B.
+ * (A - B)
+ *
+ * @param {Set|Array} the set or data to create a set from
+ * @return {Set} Updated Set
+ */
+Set.prototype.difference = function(B) {
+  if (!Set.prototype.isPrototypeOf(B))
+    B = new Set(_getValid(B, this));
+  var AList = this.toArray(),
+      check = B.has(AList), //TODO all should also accept sets
+      i,
+      l = AList.length,
+      differenceList = [];
+  for (i = 0; i < l; i++) {
+    if (!check[i])
+      differenceList.push(AList[i]);
+  }
+  //TODO not right
+  this = new Set(differenceList);
+  return this;
+};
+
+/**
+ * Update set to only include elements not in A and not in B.
+ * (A | B) - (A & B)
+ * A + B - (A & B)
+ *
+ * @param {Set|Array} the set or data to create a set from
+ * @return {Set} Updated Set
+ */
+Set.prototype.symmetricDifference = function(B) {
+  if (!Set.prototype.isPrototypeOf(B))
+    B = new Set(_getValid(B, this));
+  var BAdded = B.difference(this.clone()
+                                .intersection(B))
+                .toArray(); //needs to accept sets
+  this.difference(this.clone()
+                      .intersection(B));
+  return this.add(BAdded);
+};
+
+/**
+ * Non-modified static wrapper of Set.prototype.add()
+ *
+ * @param {Set|Array} the set or data to create a set from
+ * @param {Number|Array} values to add to the set.
+ * @return {Set} A copy or created Set with updates made.
+ */
+Set.add = function(A, d) {
+  if (!Set.prototype.isPrototypeOf(A))
+    A = new Set(_getValid(A, this));
+  return A.clone()
+          .add(d);
+};
+
+/**
+ * Non-modified static wrapper of Set.prototype.remove()
+ *
+ * @param {Set|Array} the set or data to create a set from
+ * @param {Number|Array} values to add to the set.
+ * @return {Set} A copy or created Set with updates made.
+ */
+Set.remove = function(A, d) {
+  if (!Set.prototype.isPrototypeOf(A))
+    A = new Set(_getValid(A, this));
+  var newA = A.clone(),
+  newA.remove(d);
+  return newA;
+};
+
+/**
+ * Non-modified static wrapper of Set.prototype.union()
+ *
+ * @param {Set|Array} the set or data to create a set from
+ * @param {Set|Array} the set to union with A, or data to create set from
+ * @return {Set} A copy or created Set with updates made.
+ */
+Set.union = function(A, B) {
+  if (!Set.prototype.isPrototypeOf(A))
+    A = new Set(_getValid(A, this));
+  return A.clone()
+          .union(B);
+};
+
+/**
+ * Non-modified static wrapper of Set.prototype.intersection()
+ *
+ * @param {Set|Array} the set or data to create a set from
+ * @param {Set|Array} the set to union with A, or data to create set from
+ * @return {Set} A copy or created Set with updates made.
+ */
+Set.intersection = function(A, B) {
+  if (!Set.prototype.isPrototypeOf(A))
+    A = new Set(_getValid(A, this));
+  return A.clone()
+          .intersection(B);
+};
+
+/**
+ * Non-modified static wrapper of Set.prototype.union()
+ *
+ * @param {Set|Array} the set or data to create a set from
+ * @param {Set|Array} the set to union with A, or data to create set from
+ * @return {Set} A copy or created Set with updates made.
+ */
+Set.difference = function(A, B) {
+  if (!Set.prototype.isPrototypeOf(A))
+    A = new Set(_getValid(A, this));
+  return A.clone()
+          .difference(B);
+};
+
+/**
+ * Non-modified static wrapper of Set.prototype.union()
+ *
+ * @param {Set|Array} the set or data to create a set from
+ * @param {Set|Array} the set to union with A, or data to create set from
+ * @return {Set} A copy or created Set with updates made.
+ */
+
+
+
+Set.symmetricDifference = function(A, B) {
+  if (!Set.prototype.isPrototypeOf(A))
+    A = new Set(_getValid(A, this));
+  return A.clone()
+          .symmetricDifference(B);
+};
\ No newline at end of file
diff --git a/test/set.test.js b/test/set.test.js
new file mode 100644
index 0000000..e69de29