Index: boost/program_options/cmdline.hpp
===================================================================
--- boost/program_options/cmdline.hpp	(revision 79302)
+++ boost/program_options/cmdline.hpp	(working copy)
@@ -20,8 +20,12 @@
     It's possible to introduce long options by the same character as
     short options, see allow_long_disguise.
 
-    Finally, guessing (specifying only prefix of option) and case
+    Guessing (specifying only prefix of option) and case
     insensitive processing are supported.
+
+    Enabling and disabling interspersed arguments is also supported; with
+    interspersed arguments disabled, everything after the first positional
+    argument is treated as positional.
     */
     enum style_t {
         /// Allow "--long_name" style
@@ -75,6 +79,11 @@
             e.g <tt>-foo=10</tt>
         */
         allow_long_disguise = short_case_insensitive << 1,
+        /** Disallowing interspersed arguments, e.g. <tt>mycmd file1 --opt</tt>
+            will treat <tt>--opt</tt> as an option instead of a positional
+            argument.
+        */
+        disallow_interspersed = allow_long_disguise << 1,
         /** The more-or-less traditional unix style. */
         unix_style = (allow_short | short_allow_adjacent | short_allow_next
                       | allow_long | long_allow_adjacent | long_allow_next
Index: boost/program_options/detail/cmdline.hpp
===================================================================
--- boost/program_options/detail/cmdline.hpp	(revision 79302)
+++ boost/program_options/detail/cmdline.hpp	(working copy)
@@ -107,7 +107,7 @@
         std::vector<option> parse_disguised_long_option(
             std::vector<std::string>& args);
         std::vector<option> parse_terminator(
-            std::vector<std::string>& args);
+            std::vector<std::string>& args, bool always_stop);
         std::vector<option> handle_additional_parser(
             std::vector<std::string>& args);
 
Index: libs/program_options/test/positional_options_test.cpp
===================================================================
--- libs/program_options/test/positional_options_test.cpp	(revision 79302)
+++ libs/program_options/test/positional_options_test.cpp	(working copy)
@@ -5,8 +5,11 @@
 
 #include <boost/program_options/positional_options.hpp>
 #include <boost/program_options/options_description.hpp>
+#include <boost/program_options/variables_map.hpp>
 #include <boost/program_options/parsers.hpp>
+#include <boost/program_options/cmdline.hpp>
 using namespace boost::program_options;
+using namespace boost::program_options::command_line_style;
 // We'll use po::value everywhere to workaround vc6 bug.
 namespace po = boost::program_options;
 
@@ -82,9 +85,60 @@
                       too_many_positional_options_error);
 }
 
+
+void test_interspersed()
+{
+    options_description desc;
+    desc.add_options()
+        ("first", po::value<int>())
+        ("second", po::value<int>())
+        ("positionals", po::value< vector<string> >())
+    ;
+
+    positional_options_description p;
+    p.add("positionals", -1);
+
+    vector<string> args;
+    args.push_back("--first=10");
+    args.push_back("file1");
+    args.push_back("--second=10");
+    args.push_back("file2");
+
+    // Check that --second was recognized as the second option
+    variables_map vm;
+    store(command_line_parser(args).options(desc).positional(p).run(),
+          vm);
+    notify(vm);
+
+    BOOST_CHECK_EQUAL(vm.count("first"), 1);
+    BOOST_CHECK_EQUAL(vm.count("second"), 1);
+    vector<string> positionals = vm["positionals"].as<vector<string> >();
+    BOOST_REQUIRE(positionals.size() == 2);
+    BOOST_CHECK_EQUAL(positionals[0], "file1");
+    BOOST_CHECK_EQUAL(positionals[1], "file2");
+
+    // Now check that --second was NOT recognized as the second option, but
+    // as the second positional
+    style_t style = style_t(default_style | disallow_interspersed);
+    vm.clear();
+    store(command_line_parser(args).options(desc).positional(p).style(style).run(),
+          vm);
+    notify(vm);
+
+    BOOST_CHECK_EQUAL(vm.count("first"), 1);
+    BOOST_CHECK_EQUAL(vm.count("second"), 0);
+    positionals = vm["positionals"].as<vector<string> >();
+    BOOST_REQUIRE(positionals.size() == 3);
+    BOOST_CHECK_EQUAL(positionals[0], "file1");
+    BOOST_CHECK_EQUAL(positionals[1], "--second=10");
+    BOOST_CHECK_EQUAL(positionals[2], "file2");
+}
+
+
 int main(int, char* [])
 {
     test_positional_options();
+    test_interspersed();
     test_parsing();
     return 0;
 }
Index: libs/program_options/src/cmdline.cpp
===================================================================
--- libs/program_options/src/cmdline.cpp	(revision 79302)
+++ libs/program_options/src/cmdline.cpp	(working copy)
@@ -241,7 +241,8 @@
         if ((m_style & allow_short) && (m_style & allow_slash_for_short))
             style_parsers.push_back(boost::bind(&cmdline::parse_dos_option, this, _1));
 
-        style_parsers.push_back(boost::bind(&cmdline::parse_terminator, this, _1));
+        bool always_stop = m_style & disallow_interspersed;
+        style_parsers.push_back(boost::bind(&cmdline::parse_terminator, this, _1, always_stop));
 
         vector<option> result;
         while(!args.empty())
@@ -664,13 +665,15 @@
     }
 
     vector<option> 
-    cmdline::parse_terminator(vector<string>& args)
+    cmdline::parse_terminator(vector<string>& args, bool always_stop)
     {
         vector<option> result;
         const string& tok = args[0];
-        if (tok == "--")
+        if (tok == "--" || always_stop)
         {
-            for(unsigned i = 1; i < args.size(); ++i)
+            // Starting at index 1 skips the --.
+            unsigned start = tok == "--" ? 1 : 0;
+            for(unsigned i = start; i < args.size(); ++i)
             {
                 option opt;
                 opt.value.push_back(args[i]);