diff --git a/include/boost/detail/is_sorted.hpp b/include/boost/detail/is_sorted.hpp
new file mode 100644
index 0000000..91f254c
--- /dev/null
+++ b/include/boost/detail/is_sorted.hpp
@@ -0,0 +1,56 @@
+/*==============================================================================
+    Copyright (c) 2010-2011 Bryce Lelbach
+
+    Distributed under the Boost Software License, Version 1.0. (See accompanying
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+==============================================================================*/
+
+#ifndef BOOST_DETAIL_SORTED_HPP
+#define BOOST_DETAIL_SORTED_HPP
+
+#include <boost/detail/iterator.hpp>
+
+#include <functional>
+
+namespace boost {
+namespace detail {
+
+template<class Iterator, class Comp>
+inline Iterator is_sorted_until (Iterator first, Iterator last, Comp compare) {
+  if (first == last)
+    return last;
+
+  Iterator it = first; ++it;
+
+  for (; it != last; first = it, ++it)
+    if (compare(*it, *first))
+      return it;
+
+  return it;
+}
+
+template<class Iterator>
+inline Iterator is_sorted_until (Iterator first, Iterator last) {
+  typedef typename boost::detail::iterator_traits<Iterator>::value_type
+    value_type;
+
+  typedef std::less<value_type> compare; 
+
+  return is_sorted_until(first, last, compare()); 
+}
+
+template<class Iterator, class Comp>
+inline bool is_sorted (Iterator first, Iterator last, Comp compare) {
+  return is_sorted_until(first, last, compare) == last;
+} 
+
+template<class Iterator>
+inline bool is_sorted (Iterator first, Iterator last) {
+  return is_sorted_until(first, last) == last;
+} 
+
+} // detail
+} // boost
+
+#endif // BOOST_DETAIL_SORTED_HPP
+
diff --git a/test/is_sorted_test.cpp b/test/is_sorted_test.cpp
new file mode 100644
index 0000000..36c03bc
--- /dev/null
+++ b/test/is_sorted_test.cpp
@@ -0,0 +1,129 @@
+/*==============================================================================
+    Copyright (c) 2010-2011 Bryce Lelbach
+
+    Distributed under the Boost Software License, Version 1.0. (See accompanying
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+==============================================================================*/
+
+#include <ios>
+#include <boost/config.hpp>
+#include <boost/array.hpp>
+#include <boost/detail/is_sorted.hpp>
+#include <boost/detail/lightweight_test.hpp>
+
+template<class T>
+struct tracking_less: std::binary_function <T, T, bool> {
+  typedef bool result_type;
+
+  #if defined(__PATHSCALE__)
+  tracking_less (void) { }
+  ~tracking_less (void) { }
+  #endif
+
+  bool operator() (T const& x, T const& y) const {
+    std::cout << x << " < " << y << " == " << (x < y) << "\n"; 
+    return x < y;
+  }
+};
+
+template<class T>
+struct tracking_less_equal: std::binary_function <T, T, bool> {
+  typedef bool result_type;
+
+  #if defined(__PATHSCALE__)
+  tracking_less_equal (void) { }
+  ~tracking_less_equal (void) { }
+  #endif
+
+  bool operator() (T const& x, T const& y) const {
+    std::cout << x << " <= " << y << " == " << (x <= y) << "\n"; 
+    return x <= y;
+  }
+};
+
+template<class T>
+struct tracking_greater: std::binary_function <T, T, bool> {
+  typedef bool result_type;
+
+  #if defined(__PATHSCALE__)
+  tracking_greater (void) { }
+  ~tracking_greater (void) { }
+  #endif
+
+  bool operator() (T const& x, T const& y) const {
+    std::cout << x << " > " << y << " == " << (x > y) << "\n"; 
+    return x > y;
+  }
+};
+
+template<class T>
+struct tracking_greater_equal: std::binary_function <T, T, bool> {
+  typedef bool result_type;
+
+  #if defined(__PATHSCALE__)
+  tracking_greater_equal (void) { }
+  ~tracking_greater_equal (void) { }
+  #endif
+
+  bool operator() (T const& x, T const& y) const {
+    std::cout << x << " >= " << y << " == " << (x >= y) << "\n"; 
+    return x >= y;
+  }
+};
+
+int main (void) {
+  using boost::detail::is_sorted;
+  using boost::detail::is_sorted_until;
+  using boost::array;
+  using boost::report_errors;
+
+  std::cout << std::boolalpha;
+
+  array<int, 10> a = { { 0, 1, 2,  3,  4, 5, 6,  7,  8,   9  } };
+  array<int, 10> b = { { 0, 1, 1,  2,  5, 8, 13, 34, 55,  89 } };
+  array<int, 10> c = { { 0, 1, -1, 2, -3, 5, -8, 13, -21, 34 } };
+
+  tracking_less<int> lt;
+  tracking_less_equal<int> lte;
+  tracking_greater<int> gt;
+  tracking_greater_equal<int> gte;
+
+  BOOST_TEST_EQ(is_sorted_until(a.begin(), a.end()),          a.end());
+  BOOST_TEST_EQ(is_sorted_until(a.begin(), a.end(), lt),      a.end());
+  BOOST_TEST_EQ(is_sorted_until(a.begin(), a.end(), lte),     a.end());
+  BOOST_TEST_EQ(*is_sorted_until(a.rbegin(), a.rend(), gt),   *a.rend());
+  BOOST_TEST_EQ(*is_sorted_until(a.rbegin(), a.rend(), gte),  *a.rend());
+  
+  BOOST_TEST_EQ(is_sorted(a.begin(), a.end()),        true);
+  BOOST_TEST_EQ(is_sorted(a.begin(), a.end(), lt),    true);
+  BOOST_TEST_EQ(is_sorted(a.begin(), a.end(), lte),   true);
+  BOOST_TEST_EQ(is_sorted(a.rbegin(), a.rend(), gt),  true);
+  BOOST_TEST_EQ(is_sorted(a.rbegin(), a.rend(), gte), true);
+
+  BOOST_TEST_EQ(is_sorted_until(b.begin(), b.end()),          b.end());
+  BOOST_TEST_EQ(is_sorted_until(b.begin(), b.end(), lt),      b.end());
+  BOOST_TEST_EQ(is_sorted_until(b.begin(), b.end(), lte),     &b[2]);
+  BOOST_TEST_EQ(*is_sorted_until(b.rbegin(), b.rend(), gt),   *b.rend());
+  BOOST_TEST_EQ(*is_sorted_until(b.rbegin(), b.rend(), gte),  b[2]);
+  
+  BOOST_TEST_EQ(is_sorted(b.begin(), b.end()),        true); 
+  BOOST_TEST_EQ(is_sorted(b.begin(), b.end(), lt),    true); 
+  BOOST_TEST_EQ(is_sorted(b.begin(), b.end(), lte),   false); 
+  BOOST_TEST_EQ(is_sorted(b.rbegin(), b.rend(), gt),  true);
+  BOOST_TEST_EQ(is_sorted(b.rbegin(), b.rend(), gte), false); 
+
+  BOOST_TEST_EQ(is_sorted_until(c.begin(), c.end()),          &c[2]);
+  BOOST_TEST_EQ(is_sorted_until(c.begin(), c.end(), lt),      &c[2]);
+  BOOST_TEST_EQ(is_sorted_until(c.begin(), c.end(), lte),     &c[2]);
+  BOOST_TEST_EQ(*is_sorted_until(c.rbegin(), c.rend(), gt),   c[7]);
+  BOOST_TEST_EQ(*is_sorted_until(c.rbegin(), c.rend(), gte),  c[7]);
+  
+  BOOST_TEST_EQ(is_sorted(c.begin(), c.end()),        false);
+  BOOST_TEST_EQ(is_sorted(c.begin(), c.end(), lt),    false);
+  BOOST_TEST_EQ(is_sorted(c.begin(), c.end(), lte),   false);
+  BOOST_TEST_EQ(is_sorted(c.rbegin(), c.rend(), gt),  false);
+  BOOST_TEST_EQ(is_sorted(c.rbegin(), c.rend(), gte), false);
+
+  return report_errors();
+}
+