diff --git a/lib/earmark.ex b/lib/earmark.ex
index 19cfc507..77407109 100644
--- a/lib/earmark.ex
+++ b/lib/earmark.ex
@@ -266,6 +266,7 @@ defmodule Earmark do
   """
 
   alias Earmark.Options
+  alias Earmark.Context
   import Earmark.Message, only: [emit_messages: 1, sort_messages: 1]
 
   @doc """
@@ -306,6 +307,7 @@ defmodule Earmark do
       Earmark.as_html(original, %Options{smartypants: false})
 
   """
+  @spec as_html(String.t | list(String.t), %Options{}) :: {:ok, String.t, list()} | {:error, String.t, list(String.t)}
   def as_html(lines, options \\ %Options{}) do
     {context, html} = _as_html(lines, options)
     case sort_messages(context) do
@@ -320,6 +322,7 @@ defmodule Earmark do
 
   Otherwise it behaves exactly as `as_html`.
   """
+  @spec as_html!(String.t | list(String.t), %Options{}) :: String.t
   def as_html!(lines, options \\ %Options{})
   def as_html!(lines, options = %Options{}) do
     {context, html} = _as_html(lines, options)
@@ -327,6 +330,7 @@ defmodule Earmark do
     html
   end
 
+  @spec _as_html(String.t | list(String.t), %Options{}) :: {%Context{}, String.t}
   defp _as_html(lines, options) do
     {blocks, context} = parse(lines, options)
     case blocks do
@@ -344,6 +348,7 @@ defmodule Earmark do
   for more details.
   """
 
+  @spec parse(String.t | list(String.t), %Options{}) :: { Earmark.Block.ts, %Context{} }
   def parse(lines, options \\ %Earmark.Options{})
   def parse(lines, options = %Options{mapper: mapper}) when is_list(lines) do
     { blocks, links, options1 } = Earmark.Parser.parse(lines, options, false)
@@ -377,6 +382,7 @@ defmodule Earmark do
   end
 
   @doc false
+  @spec pmap( list(A), (A -> Earmark.Line.t) ) :: Earmark.Line.ts
   def pmap(collection, func) do
    collection
     |> Enum.map(fn item -> Task.async(fn -> func.(item) end) end)
diff --git a/lib/earmark/block.ex b/lib/earmark/block.ex
index 5cd9bfde..518be2cd 100644
--- a/lib/earmark/block.ex
+++ b/lib/earmark/block.ex
@@ -51,6 +51,7 @@ defmodule Earmark.Block do
   # Then extract any id definitions, and build a map from them. Not
   # for external consumption.
 
+  @spec parse( Line.ts, Options.t ) :: {ts, %{}, Options.t}
   def parse(lines, options) do
     {blocks, options} = lines |> remove_trailing_blank_lines() |> lines_to_blocks(options)
     links  = links_from_blocks(blocks)
@@ -66,6 +67,7 @@ defmodule Earmark.Block do
   end
 
 
+  @spec _parse(Line.ts, ts, Options.t) :: {ts, Earmark.Message.ts}
   defp _parse([], result, options), do: {result, options}
 
   ###################
@@ -331,6 +333,7 @@ defmodule Earmark.Block do
   # Assign attributes that follow a block to that block #
   #######################################################
 
+  @spec assign_attributes_to_blocks( ts, ts ) :: ts
   def assign_attributes_to_blocks([], result), do: Enum.reverse(result)
 
   def assign_attributes_to_blocks([ %Ial{attrs: attrs}, block | rest], result) do
@@ -349,6 +352,7 @@ defmodule Earmark.Block do
   # @spec consolidate_para( ts ) :: { ts, ts, {nil | String.t, number} }
   defp consolidate_para( lines ), do: _consolidate_para( lines, [], @not_pending )
 
+  @spec _consolidate_para( ts, ts, inline_code_continuation ) :: { ts, ts, inline_code_continuation }
   defp _consolidate_para( [], result, pending ) do
     {result, [], pending}
   end
@@ -365,6 +369,7 @@ defmodule Earmark.Block do
   # Consolidate one or more list items into a list #
   ##################################################
 
+  @spec consolidate_list_items( ts, ts ) :: ts
   defp consolidate_list_items([], result) do
     result |> Enum.map(&compute_list_spacing/1)  # no need to reverse
   end
@@ -405,6 +410,7 @@ defmodule Earmark.Block do
   # Read in a table (consecutive TableLines with
   # the same number of columns)
 
+  @spec read_table( ts, number, %Table{} ) :: { %Table{}, ts }
   defp read_table([ %Line.TableLine{columns: cols} | rest ],
                     col_count,
                     table = %Table{})
@@ -426,6 +432,7 @@ defmodule Earmark.Block do
   end
 
 
+  @spec look_for_alignments( [String.t] ) :: atom
   defp look_for_alignments([ _first, second | _rest ]) do
     if Enum.all?(second, fn row -> row =~ ~r{^:?-+:?$} end) do
       second
@@ -451,6 +458,7 @@ defmodule Earmark.Block do
     visit(blocks, Map.new, &link_extractor/2)
   end
 
+  @spec link_extractor(t, %{}) :: %{}
   defp link_extractor(item = %IdDef{id: id}, result) do
     Map.put(result, String.downcase(id), item)
   end
@@ -462,6 +470,7 @@ defmodule Earmark.Block do
   # Visitor pattern for each block #
   ##################################
 
+  @spec visit(ts, %{}, (t, %{} -> %{})) :: %{}
   defp visit([], result, _func), do: result
 
   # Structural node BlockQuote -> descend
@@ -534,6 +543,7 @@ defmodule Earmark.Block do
 
 
   # (_,{'nil' | binary(),number()}) -> #{}jj
+  @spec inline_or_text?( Line.t, inline_code_continuation ) :: %{pending: String.t, continue: boolean}
   defp inline_or_text?(line, pending)
   defp inline_or_text?(line = %Line.Text{}, @not_pending) do
     pending = opens_inline_code(line)
diff --git a/lib/earmark/helpers/attr_parser.ex b/lib/earmark/helpers/attr_parser.ex
index 53251036..875968bc 100644
--- a/lib/earmark/helpers/attr_parser.ex
+++ b/lib/earmark/helpers/attr_parser.ex
@@ -3,8 +3,11 @@ defmodule Earmark.Helpers.AttrParser do
   import Earmark.Helpers.StringHelpers, only: [ behead: 2 ]
   import Earmark.Message, only: [add_message: 2]
 
+  alias Earmark.Context
+
   @type errorlist :: list(String.t)
 
+  @spec parse_attrs(Context.t, String.t, number()) :: {map, errorlist}
   def parse_attrs(context, attrs, lnb) do
     { attrs, errors } = _parse_attrs(%{}, attrs, [], lnb)
     { add_errors(context, errors, lnb), attrs }
diff --git a/lib/earmark/helpers/line_helpers.ex b/lib/earmark/helpers/line_helpers.ex
index aefed66c..eadd69d5 100644
--- a/lib/earmark/helpers/line_helpers.ex
+++ b/lib/earmark/helpers/line_helpers.ex
@@ -2,6 +2,7 @@ defmodule Earmark.Helpers.LineHelpers do
 
   alias Earmark.Line
 
+  @spec blank?(Line.t) :: boolean
   def blank?(%Line.Blank{}),   do: true
   def blank?(_),               do: false
 
diff --git a/lib/earmark/helpers/lookahead_helpers.ex b/lib/earmark/helpers/lookahead_helpers.ex
index 71f47c46..8b98af79 100644
--- a/lib/earmark/helpers/lookahead_helpers.ex
+++ b/lib/earmark/helpers/lookahead_helpers.ex
@@ -14,6 +14,7 @@ defmodule Earmark.Helpers.LookaheadHelpers do
 
   Otherwise `{nil, 0}` is returned
   """
+  @spec opens_inline_code(numbered_line) :: inline_code_continuation
   def opens_inline_code( %{line: line, lnb: lnb} ) do
     case tokenize(line, with: :string_lexer) |> has_still_opening_backtix(nil) do
       nil      -> {nil, 0}
@@ -29,6 +30,7 @@ defmodule Earmark.Helpers.LookaheadHelpers do
   opening backtix
   """
   # (#{},{_,_}) -> {_,_}
+  @spec still_inline_code(numbered_line, inline_code_continuation) :: inline_code_continuation
   def still_inline_code( %{line: line, lnb: lnb}, old = {pending, _pending_lnb} ) do
     case tokenize(line, with: :string_lexer) |> has_still_opening_backtix({:old, pending}) do
       nil -> {nil, 0}
@@ -56,6 +58,7 @@ defmodule Earmark.Helpers.LookaheadHelpers do
   #######################################################################################
   # read_list_lines
   #######################################################################################
+  @spec read_list_lines( Line.ts, inline_code_continuation, number ) :: {boolean, Line.ts, Line.ts, number, number}
   @doc """
   Called to slurp in the lines for a list item.
   basically, we allow indents and blank lines, and
@@ -69,6 +72,7 @@ defmodule Earmark.Helpers.LookaheadHelpers do
 
   @type read_list_info :: %{pending: maybe(String.t), pending_lnb: number, initial_indent: number, min_indent: maybe(number)}
 
+  @spec _read_list_lines(Line.ts, Line.ts, read_list_info) :: {boolean, Line.ts, Line.ts, number}
   # List items with initial_indent + 2
   defp _read_list_lines([ line = %Line.ListItem{initial_indent: li_indent} | rest ], result,
     params=%{pending: nil, initial_indent: initial_indent, min_indent: min_indent})
diff --git a/lib/earmark/helpers/string_helpers.ex b/lib/earmark/helpers/string_helpers.ex
index 900bca17..9e4d0379 100644
--- a/lib/earmark/helpers/string_helpers.ex
+++ b/lib/earmark/helpers/string_helpers.ex
@@ -17,6 +17,7 @@ defmodule Earmark.Helpers.StringHelpers do
         iex> behead_tuple("prefixpostfix", "prefix")
         {"prefix", "postfix"}
   """
+  @spec behead_tuple( String.t, String.t ) :: {String.t, String.t}
   def behead_tuple(str, lead) do
     {lead, behead(str, lead)}
   end
diff --git a/lib/earmark/line.ex b/lib/earmark/line.ex
index 3b2ed97d..1607a8d6 100644
--- a/lib/earmark/line.ex
+++ b/lib/earmark/line.ex
@@ -75,6 +75,7 @@ defmodule Earmark.Line do
   # proceeding
 
   # (_,atom() | tuple() | #{},_) -> ['Elixir.B']
+  @spec scan_lines( list(String.t), %Earmark.Options{}, boolean ) :: ts
   def scan_lines lines, options \\ %Earmark.Options{}, recursive \\ false
   def scan_lines lines, options, recursive do
     lines_with_count( lines, options.line - 1)
diff --git a/lib/earmark/message.ex b/lib/earmark/message.ex
index e6401f34..06012a11 100644
--- a/lib/earmark/message.ex
+++ b/lib/earmark/message.ex
@@ -8,9 +8,11 @@ defmodule Earmark.Message do
   @type ts:: list(t)
   @type container_type :: Options.t | Context.t
 
+  @spec add_messages(container_type, ts) :: container_type
   def add_messages(container, messages), do:
     Enum.reduce(messages, container, &(add_message(&2, &1)))
 
+  @spec add_message(container_type, t) :: container_type
   def add_message(container, message)
   def add_message(options = %Options{}, message) do
     %{options | messages: [message | options.messages]}
@@ -19,14 +21,17 @@ defmodule Earmark.Message do
     %{context | options: %{context.options | messages: [message | get_messages(context)]}}
   end
   
+  @spec add_messages_from(Context.t, Context.t) :: Context.t
   def add_messages_from(context, message_container) do
     add_messages(context, message_container.options.messages)
   end
 
+  @spec get_messages( container_type ) :: ts
   def get_messages(container)
   def get_messages(%Context{options: %{messages: messages}}), do: messages
   def get_messages(%Options{messages: messages}),             do: messages
 
+  @spec set_messages( Context.t, ts ) :: Context.t
   def set_messages(container, messages)
   def set_messages(c = %Context{}, messages), do: put_in(c.options.messages, messages)
 
@@ -49,6 +54,7 @@ defmodule Earmark.Message do
   defp emit_message(filename, msg), do:
     IO.puts(:stderr, format_message(filename, msg))
 
+  @spec format_message( String.t, t ) :: String.t
   defp format_message filename, {type, line, text} do
     "#{filename}:#{line}: #{type}: #{text}"
   end
diff --git a/lib/earmark/parser.ex b/lib/earmark/parser.ex
index 4ab55d04..2c7efa53 100644
--- a/lib/earmark/parser.ex
+++ b/lib/earmark/parser.ex
@@ -5,6 +5,7 @@ defmodule Earmark.Parser do
   import Earmark.Message, only: [add_messages: 2]
 
 
+  @spec parse(list(String.t), %Earmark.Options{}, boolean) :: {Block.ts(), %{}}
   def parse(text_lines), do: parse(text_lines, %Earmark.Options{}, false)
 
   def parse(text_lines, options = %Earmark.Options{}, recursive) do
@@ -30,9 +31,11 @@ defmodule Earmark.Parser do
     { blocks, footnotes, options1 }
   end
 
+  @spec footnote_def?( Block.t )::boolean
   defp footnote_def?(%Block.FnDef{}), do: true
   defp footnote_def?(_block), do: false
 
+  @spec find_footnote_links(Block.t) :: list(String.t)
   defp find_footnote_links(%Block.Para{lines: lines, lnb: lnb}) do
     lines
     |> Enum.zip(Stream.iterate(lnb, &(&1 + 1)))
@@ -43,6 +46,7 @@ defmodule Earmark.Parser do
   end
   defp find_footnote_links(_), do: []
 
+  @spec extract_footnote_links({String.t, number()}) :: list({String.t, number()})
   defp extract_footnote_links({line, lnb}) do
     Regex.scan(~r{\[\^([^\]]+)\]}, line)
     |> Enum.map(&tl/1)
@@ -50,6 +54,7 @@ defmodule Earmark.Parser do
   end
 
 
+  @spec get_footnote_numbers( list({String.t, number()} ), Block.ts, %Earmark.Options{} ) :: Block.ts
   def get_footnote_numbers(refs, footnotes, options) do
     Enum.reduce(refs, {[], []}, fn({ref, lnb}, {defined, undefined}) ->
       r = hd(ref)
@@ -62,6 +67,7 @@ defmodule Earmark.Parser do
     end)
   end
 
+  @spec create_footnote_blocks(Block.ts, Block.ts) :: Block.ts
   defp create_footnote_blocks(blocks, []), do: blocks
 
   defp create_footnote_blocks(blocks, footnotes) do
diff --git a/lib/earmark/scanner.ex b/lib/earmark/scanner.ex
index 74ae9446..08b2b658 100644
--- a/lib/earmark/scanner.ex
+++ b/lib/earmark/scanner.ex
@@ -36,6 +36,7 @@ defmodule Earmark.Scanner do
   @type t_continuation :: {token, String.t, boolean()}
 
 
+  @spec scan_line( String.t ) :: tokens
   @doc """
   Scans a line into a list of tokens
   """
@@ -44,6 +45,7 @@ defmodule Earmark.Scanner do
     |> Enum.reverse
   end
 
+  @spec scan_line_into_tokens( String.t, tokens, boolean() ) :: tokens
   # Empty Line
   defp scan_line_into_tokens "", [], _beg do
     []
@@ -56,6 +58,7 @@ defmodule Earmark.Scanner do
     scan_line_into_tokens( rest, [token|tokens], still_at_beg )
   end
 
+  @spec scan_next_token( String.t, boolean ) :: false | t_continuation
   defp scan_next_token line, beg_of_line
   defp scan_next_token line, true do
     cond do
@@ -102,6 +105,7 @@ defmodule Earmark.Scanner do
     |> Tuple.append( false )
   end
 
+  @spec scan_token_not_at_beg( String.t ) :: {} | t_continuation
   defp scan_token_not_at_beg line do
     cond do
       matches = Regex.run( @backtix_rgx, line ) ->
@@ -119,6 +123,7 @@ defmodule Earmark.Scanner do
     end
   end
 
+  @spec make_ruler_from( String.t ) :: token
   defp make_ruler_from type do
     case type do
       "*" -> %RulerFat{}
@@ -127,6 +132,7 @@ defmodule Earmark.Scanner do
     end
   end
 
+  @spec make_list_item( String.t ) :: %ListItem{}
   defp make_list_item bullet do
     case bullet do
       "*" -> %ListItem{type: :ul, bullet: "*"}
@@ -135,6 +141,7 @@ defmodule Earmark.Scanner do
     end
   end
 
+  @spec prefixed_with_ws(String.t, String.t) :: false | { %Text{}, String.t, true}
   defp prefixed_with_ws line, ws do
     if ws == "" do
       false