diff --git a/README.md b/README.md
index 8578747..393ae96 100644
--- a/README.md
+++ b/README.md
@@ -7,6 +7,16 @@ When `format` is invoked on a string, placeholders within the string are
 replaced with values determined by the arguments provided. A placeholder
 is a sequence of characters beginning with `{` and ending with `}`.
 
+## About this Fork
+dchambers's original version implemented nested variable interpolation, and
+included support for _transformations_ that would provide functionality
+similar to the _conversions_ in python's str.format()
+
+It did not implement **printf()**-style number formatting, so here I'm attempting to do that.
+At the moment, only signs, integer precision, and field padding are implemented.
+
+## Usage
+
 ### string.format(value1, value2, ..., valueN)
 
 Placeholders may contain numbers which refer to positional arguments:
diff --git a/lib/string-format.js b/lib/string-format.js
index 457694d..a42877c 100644
--- a/lib/string-format.js
+++ b/lib/string-format.js
@@ -1,7 +1,20 @@
 // Generated by CoffeeScript 1.4.0
+
+/*
+Source code and build tools for this file are available at:
+https://github.com/deleted/string-format
+
+This project attempts to implement python-style string formatting, as documented here:
+http://docs.python.org/2/library/string.html#format-string-syntax
+
+The format spec part is not complete, but it can handle field padding, float precision, and such
+*/
+
+
 (function() {
-  var format, lookup, resolve,
-    __slice = [].slice;
+  var applyFormat, format, lookup, resolve,
+    __slice = [].slice,
+    __indexOf = [].indexOf || function(item) { for (var i = 0, l = this.length; i < l; i++) { if (i in this && this[i] === item) return i; } return -1; };
 
   format = String.prototype.format = function() {
     var args, explicit, idx, implicit, message,
@@ -17,7 +30,7 @@
     idx = 0;
     explicit = implicit = false;
     message = 'cannot switch from {} to {} numbering'.format();
-    return this.replace(/([{}])\1|[{](.*?)(?:!(.+?))?[}]/g, function(match, literal, key, transformer) {
+    return this.replace(/([{}])\1|[{](.*?)(?:!([^:]+?)?)?(?::(.+?))?[}]/g, function(match, literal, key, transformer, formatSpec) {
       var fn, value, _ref, _ref1, _ref2;
       if (literal) {
         return literal;
@@ -35,7 +48,11 @@
         }
         value = (_ref1 = args[idx++]) != null ? _ref1 : '';
       }
-      value = value.toString();
+      if (formatSpec) {
+        value = applyFormat(value, formatSpec);
+      } else {
+        value = "" + value;
+      }
       if (fn = format.transformers[transformer]) {
         return (_ref2 = fn.call(value)) != null ? _ref2 : '';
       } else {
@@ -66,7 +83,86 @@
     }
   };
 
-  format.transformers = {};
+  applyFormat = function(value, formatSpec) {
+    var align, comma, fill, hash, isNumeric, pattern, precision, sign, type, width, zeropad, _ref, _ref1;
+    pattern = /([^{}](?=[<>=^]))?([<>=^])?([-+\x20])?(\#)?(0)?(\d+)?(,)?(?:\.(\d+))?([bcdeEfFgGnosxX%])?/;
+    _ref = formatSpec.match(pattern).slice(1), fill = _ref[0], align = _ref[1], sign = _ref[2], hash = _ref[3], zeropad = _ref[4], width = _ref[5], comma = _ref[6], precision = _ref[7], type = _ref[8];
+    if (zeropad) {
+      fill || (fill = '0');
+      align || (align = '=');
+    }
+    align || (align = '>');
+    fill || (fill = ' ');
+    switch (type) {
+      case 'b':
+      case 'c':
+      case 'd':
+      case 'o':
+      case 'x':
+      case 'X':
+      case 'n':
+        isNumeric = true;
+        value = '' + parseInt(value, 10);
+        break;
+      case 'e':
+      case 'E':
+      case 'f':
+      case 'F':
+      case 'g':
+      case 'G':
+      case 'n':
+      case '%':
+        isNumeric = true;
+        value = parseFloat(value);
+        if (precision) {
+          value = value.toFixed(parseInt(precision));
+        } else {
+          value = "" + value;
+        }
+        break;
+      case 's':
+        isNumeric = false;
+        value = "" + value;
+    }
+    if (isNumeric && sign) {
+      if (sign === "+" || sign === " ") {
+        if (value[0] !== '-') {
+          value = sign + value;
+        }
+      }
+    }
+    /*
+      if isNumeric and value.charAt(0) in "+-"
+        memoSign = value.charAt 0
+        value = value.substr 1
+    */
+
+    if (fill) {
+      value = '' + value;
+      while (value.length < parseInt(width)) {
+        switch (align) {
+          case '=':
+            if (_ref1 = value.charAt(0), __indexOf.call("+- ", _ref1) >= 0) {
+              value = value.charAt(0) + fill + value.slice(1);
+            } else {
+              value = fill + value;
+            }
+            break;
+          case '<':
+            value = value + fill;
+            break;
+          case '>':
+            value = fill + value;
+            break;
+          case '^':
+            throw new Error("Not implemented");
+        }
+      }
+    }
+    return value;
+  };
+
+  format.transformers || (format.transformers = {});
 
   format.version = '0.2.1';
 
diff --git a/src/string-format.coffee b/src/string-format.coffee
index 042a1d7..4745ea1 100644
--- a/src/string-format.coffee
+++ b/src/string-format.coffee
@@ -1,3 +1,13 @@
+# vim: ts=2:sw=2:expandtab
+###
+Source code and build tools for this file are available at:
+https://github.com/deleted/string-format
+
+This project attempts to implement python-style string formatting, as documented here:
+http://docs.python.org/2/library/string.html#format-string-syntax
+
+The format spec part is not complete, but it can handle field padding, float precision, and such
+###
 format = String::format = (args...) ->
 
   if args.length is 0
@@ -8,8 +18,8 @@ format = String::format = (args...) ->
   message = 'cannot switch from {} to {} numbering'.format()
 
   @replace \
-  /([{}])\1|[{](.*?)(?:!(.+?))?[}]/g,
-  (match, literal, key, transformer) ->
+  /([{}])\1|[{](.*?)(?:!([^:]+?)?)?(?::(.+?))?[}]/g,
+  (match, literal, key, transformer, formatSpec) ->
     return literal if literal
 
     if key.length
@@ -21,7 +31,10 @@ format = String::format = (args...) ->
       throw new Error message 'explicit', 'implicit' if explicit
       value = args[idx++] ? ''
 
-    value = value.toString()
+    if formatSpec
+      value = applyFormat value,  formatSpec
+    else
+      value = "#{value}"
     if fn = format.transformers[transformer] then fn.call(value) ? ''
     else value
 
@@ -37,6 +50,74 @@ resolve = (object, key) ->
   value = object[key]
   if typeof value is 'function' then value.call object else value
 
-format.transformers = {}
+# An implementation of http://docs.python.org/2/library/string.html#format-specification-mini-language
+applyFormat = (value, formatSpec) ->
+  pattern = ///
+    ([^{}](?=[<>=^]))?([<>=^])? # fill & align
+    ([-+\x20])? # sign
+    (\#)? # integer base specifier
+    (0)? # zero-padding
+    (\d+)? # width
+    (,)? # use a comma thousands-seperator
+    (?:\.(\d+))? # precision
+    ([bcdeEfFgGnosxX%])? # type
+  ///
+  [fill, align, sign, hash, zeropad, width, comma, precision, type] = formatSpec.match(pattern)[1..]
+  if zeropad
+    fill or= '0'
+    align or= '='
+  align or= '>'
+  fill or= ' '
+
+  switch type
+    when 'b', 'c', 'd', 'o', 'x', 'X', 'n' # integer
+      isNumeric = yes
+      value = '' + parseInt(value, 10)
+    when 'e','E','f','F','g','G','n','%' # float
+      isNumeric = true
+      value = parseFloat(value)
+      if precision
+        value = value.toFixed(parseInt(precision))
+      else
+        value = "#{value}"
+    when 's' #string
+      isNumeric = false
+      value = "#{value}"
+
+  if isNumeric and sign
+    if sign in ["+"," "]
+        if value[0] != '-'
+          value = sign + value
+  
+  ###
+  if isNumeric and value.charAt(0) in "+-"
+    memoSign = value.charAt 0
+    value = value.substr 1
+  ###
+
+  if fill
+    value = ''+value
+    while value.length < parseInt(width)
+      switch align
+        when '='
+          # Forces the padding to be placed after the sign (if any) but before the digits.
+          if value.charAt(0) in "+- "
+            value = value.charAt(0) + fill + value[1..]
+          else
+            value = fill + value
+        when '<'
+          # Forces the field to be left-aligned within the available space (this is the default for most objects).
+          value = value + fill
+        when '>'
+          # Forces the field to be right-aligned within the available space (this is the default for numbers).
+          value = fill + value
+        when '^'
+          throw new Error("Not implemented")
+
+    #value = if memoSign then "#{memoSign}#{value}" else value
+
+  return value
+
+format.transformers or= {}
 
 format.version = '0.2.1'
diff --git a/test/string-format.coffee b/test/string-format.coffee
index 525fc7b..92e177a 100644
--- a/test/string-format.coffee
+++ b/test/string-format.coffee
@@ -101,3 +101,21 @@ describe 'String::format', ->
     '{{{{0}}}}'.format(null).should.equal '{{0}}'
     '}}{{'.format(null).should.equal '}{'
     '}}x{{'.format(null).should.equal '}x{'
+
+  it "correctly pads integer values", ->
+    '{:4d}'.format(1).should.equal '   1'
+    '{:04d}'.format(1).should.equal '0001'
+    '{:04d}'.format(-1).should.equal '-001'
+    '{:+04d}'.format(1).should.equal '+001'
+    '{: 04d}'.format(1).should.equal ' 001'
+    '{:x>04d}'.format(1).should.equal 'xxx1'
+    '{:x<04d}'.format(1).should.equal '1xxx'
+
+  it "correctly formats floats", ->
+    '{:0}'.format(1.2345).should.equal '1.2345'
+    '{:.2f}'.format(1.2345).should.equal '1.23'
+    '{:.1f}'.format(-1.2345).should.equal '-1.2'
+    '{:+.2f}'.format(1.23456).should.equal '+1.23'
+    '{:06.2f}'.format(1.2345).should.equal '001.23'
+    '{:06.2f}'.format(-1.2345).should.equal '-01.23'
+    '{:+07.3f}'.format(1.2345).should.equal '+01.234'