diff --git a/html5lib/filters/alphabeticalattributes.py b/html5lib/filters/alphabeticalattributes.py
index 5fea9f69..5ba926e3 100644
--- a/html5lib/filters/alphabeticalattributes.py
+++ b/html5lib/filters/alphabeticalattributes.py
@@ -17,6 +17,7 @@ def _attr_key(attr):
 
 
 class Filter(base.Filter):
+    """Alphabetizes attributes for elements"""
     def __iter__(self):
         for token in base.Filter.__iter__(self):
             if token["type"] in ("StartTag", "EmptyTag"):
diff --git a/html5lib/filters/inject_meta_charset.py b/html5lib/filters/inject_meta_charset.py
index 2059ec86..aefb5c84 100644
--- a/html5lib/filters/inject_meta_charset.py
+++ b/html5lib/filters/inject_meta_charset.py
@@ -4,7 +4,15 @@
 
 
 class Filter(base.Filter):
+    """Injects ``<meta charset=ENCODING>`` tag into head of document"""
     def __init__(self, source, encoding):
+        """Creates a Filter
+
+        :arg source: the source token stream
+
+        :arg encoding: the encoding to set
+
+        """
         base.Filter.__init__(self, source)
         self.encoding = encoding
 
diff --git a/html5lib/filters/lint.py b/html5lib/filters/lint.py
index a9c0831a..acd4d7a2 100644
--- a/html5lib/filters/lint.py
+++ b/html5lib/filters/lint.py
@@ -10,7 +10,19 @@
 
 
 class Filter(base.Filter):
+    """Lints the token stream for errors
+
+    If it finds any errors, it'll raise an ``AssertionError``.
+
+    """
     def __init__(self, source, require_matching_tags=True):
+        """Creates a Filter
+
+        :arg source: the source token stream
+
+        :arg require_matching_tags: whether or not to require matching tags
+
+        """
         super(Filter, self).__init__(source)
         self.require_matching_tags = require_matching_tags
 
diff --git a/html5lib/filters/optionaltags.py b/html5lib/filters/optionaltags.py
index f6edb734..4a865012 100644
--- a/html5lib/filters/optionaltags.py
+++ b/html5lib/filters/optionaltags.py
@@ -4,6 +4,7 @@
 
 
 class Filter(base.Filter):
+    """Removes optional tags from the token stream"""
     def slider(self):
         previous1 = previous2 = None
         for token in self.source:
diff --git a/html5lib/filters/sanitizer.py b/html5lib/filters/sanitizer.py
index dc801668..6633168f 100644
--- a/html5lib/filters/sanitizer.py
+++ b/html5lib/filters/sanitizer.py
@@ -705,7 +705,7 @@
 
 
 class Filter(base.Filter):
-    """ sanitization of XHTML+MathML+SVG and of inline style attributes."""
+    """Sanitizes token stream of XHTML+MathML+SVG and of inline style attributes"""
     def __init__(self,
                  source,
                  allowed_elements=allowed_elements,
@@ -718,6 +718,37 @@ def __init__(self,
                  attr_val_is_uri=attr_val_is_uri,
                  svg_attr_val_allows_ref=svg_attr_val_allows_ref,
                  svg_allow_local_href=svg_allow_local_href):
+        """Creates a Filter
+
+        :arg allowed_elements: set of elements to allow--everything else will
+            be escaped
+
+        :arg allowed_attributes: set of attributes to allow in
+            elements--everything else will be stripped
+
+        :arg allowed_css_properties: set of CSS properties to allow--everything
+            else will be stripped
+
+        :arg allowed_css_keywords: set of CSS keywords to allow--everything
+            else will be stripped
+
+        :arg allowed_svg_properties: set of SVG properties to allow--everything
+            else will be removed
+
+        :arg allowed_protocols: set of allowed protocols for URIs
+
+        :arg allowed_content_types: set of allowed content types for ``data`` URIs.
+
+        :arg attr_val_is_uri: set of attributes that have URI values--values
+            that have a scheme not listed in ``allowed_protocols`` are removed
+
+        :arg svg_attr_val_allows_ref: set of SVG attributes that can have
+            references
+
+        :arg svg_allow_local_href: set of SVG elements that can have local
+            hrefs--these are removed
+
+        """
         super(Filter, self).__init__(source)
         self.allowed_elements = allowed_elements
         self.allowed_attributes = allowed_attributes
@@ -737,11 +768,11 @@ def __iter__(self):
                 yield token
 
     # Sanitize the +html+, escaping all elements not in ALLOWED_ELEMENTS, and
-    # stripping out all # attributes not in ALLOWED_ATTRIBUTES. Style
-    # attributes are parsed, and a restricted set, # specified by
-    # ALLOWED_CSS_PROPERTIES and ALLOWED_CSS_KEYWORDS, are allowed through.
-    # attributes in ATTR_VAL_IS_URI are scanned, and only URI schemes specified
-    # in ALLOWED_PROTOCOLS are allowed.
+    # stripping out all attributes not in ALLOWED_ATTRIBUTES. Style attributes
+    # are parsed, and a restricted set, specified by ALLOWED_CSS_PROPERTIES and
+    # ALLOWED_CSS_KEYWORDS, are allowed through. attributes in ATTR_VAL_IS_URI
+    # are scanned, and only URI schemes specified in ALLOWED_PROTOCOLS are
+    # allowed.
     #
     #   sanitize_html('<script> do_nasty_stuff() </script>')
     #    => &lt;script> do_nasty_stuff() &lt;/script>
diff --git a/html5lib/filters/whitespace.py b/html5lib/filters/whitespace.py
index 89210528..0d12584b 100644
--- a/html5lib/filters/whitespace.py
+++ b/html5lib/filters/whitespace.py
@@ -10,7 +10,7 @@
 
 
 class Filter(base.Filter):
-
+    """Collapses whitespace except in pre, textarea, and script elements"""
     spacePreserveElements = frozenset(["pre", "textarea"] + list(rcdataElements))
 
     def __iter__(self):