diff --git a/Source/cmAbstractFilesCommand.h b/Source/cmAbstractFilesCommand.h
index 6e7f73e49..a40cce891 100644
--- a/Source/cmAbstractFilesCommand.h
+++ b/Source/cmAbstractFilesCommand.h
@@ -54,6 +54,8 @@ public:
       return
         "ABSTRACT_FILES(file1 file2 ..)";
     }
+  
+  cmTypeMacro(cmAbstractFilesCommand, cmCommand);
 };
 
 
diff --git a/Source/cmAddTargetCommand.h b/Source/cmAddTargetCommand.h
index 01653e625..fd0aeab68 100644
--- a/Source/cmAddTargetCommand.h
+++ b/Source/cmAddTargetCommand.h
@@ -65,6 +65,8 @@ public:
     return
       "ADD_TARGET(Name \"command to run\")";
     }
+  
+  cmTypeMacro(cmAddTargetCommand, cmCommand);
 };
 
 #endif
diff --git a/Source/cmAuxSourceDirectoryCommand.h b/Source/cmAuxSourceDirectoryCommand.h
index c830a769a..905d63ab9 100644
--- a/Source/cmAuxSourceDirectoryCommand.h
+++ b/Source/cmAuxSourceDirectoryCommand.h
@@ -67,6 +67,8 @@ public:
     return
       "AUX_SOURCE_DIRECTORY(dir)";
     }
+  
+  cmTypeMacro(cmAuxSourceDirectoryCommand, cmCommand);
 };
 
 
diff --git a/Source/cmCommand.h b/Source/cmCommand.h
index aefd757bd..55841c432 100644
--- a/Source/cmCommand.h
+++ b/Source/cmCommand.h
@@ -122,6 +122,19 @@ public:
   const char* GetError() 
     {return m_Error.c_str();}
 
+  /**
+   * Returns true if this class is the given class, or a subclass of it.
+   */
+  static bool IsTypeOf(const char *type)
+    { return !strcmp("cmCommand", type); }
+  
+  /**
+   * Returns true if this object is an instance of the given class or
+   * a subclass of it.
+   */
+  virtual bool IsA(const char *type)
+    { return cmCommand::IsTypeOf(type); }
+
 protected:
   void SetError(const char* e)
     {
@@ -136,4 +149,28 @@ private:
   std::string m_Error;
 };
 
+// All subclasses of cmCommand should invoke this macro.
+#define cmTypeMacro(thisClass,superclass) \
+static bool IsTypeOf(const char *type) \
+{ \
+  if ( !strcmp(#thisClass,type) ) \
+    { \
+    return true; \
+    } \
+  return superclass::IsTypeOf(type); \
+} \
+virtual bool IsA(const char *type) \
+{ \
+  return thisClass::IsTypeOf(type); \
+} \
+static thisClass* SafeDownCast(cmCommand *c) \
+{ \
+  if ( c && c->IsA(#thisClass) ) \
+    { \
+    return (thisClass *)c; \
+    } \
+  return 0;\
+}
+
+
 #endif
diff --git a/Source/cmExecutablesCommand.h b/Source/cmExecutablesCommand.h
index c420a878c..48b013ffa 100644
--- a/Source/cmExecutablesCommand.h
+++ b/Source/cmExecutablesCommand.h
@@ -63,6 +63,8 @@ public:
     return
       "EXECUTABLES(file1 file2 ...)";
     }
+  
+  cmTypeMacro(cmExecutablesCommand, cmCommand);
 };
 
 
diff --git a/Source/cmFindIncludeCommand.h b/Source/cmFindIncludeCommand.h
index 4b2cd4a68..738103293 100644
--- a/Source/cmFindIncludeCommand.h
+++ b/Source/cmFindIncludeCommand.h
@@ -70,6 +70,8 @@ public:
     return
       "FIND_INCLUDE(DEFINE try1 try2 ...)";
     }
+  
+  cmTypeMacro(cmFindIncludeCommand, cmCommand);
 };
 
 
diff --git a/Source/cmFindLibraryCommand.h b/Source/cmFindLibraryCommand.h
index eca2e60b8..f1e26a28e 100644
--- a/Source/cmFindLibraryCommand.h
+++ b/Source/cmFindLibraryCommand.h
@@ -71,6 +71,8 @@ public:
     return
       "FIND_LIBRARY(DEFINE libraryName path1 path2 path3...)";
     }
+  
+  cmTypeMacro(cmFindLibraryCommand, cmCommand);
 };
 
 
diff --git a/Source/cmFindProgramCommand.h b/Source/cmFindProgramCommand.h
index 8aa7ee9ce..4b6d58cad 100644
--- a/Source/cmFindProgramCommand.h
+++ b/Source/cmFindProgramCommand.h
@@ -71,6 +71,8 @@ public:
     return
       "FIND_PROGRAM(NAME executable1 executable2 ...)";
     }
+  
+  cmTypeMacro(cmFindProgramCommand, cmCommand);
 };
 
 
diff --git a/Source/cmIncludeDirectoryCommand.h b/Source/cmIncludeDirectoryCommand.h
index 4236880c0..8011e533a 100644
--- a/Source/cmIncludeDirectoryCommand.h
+++ b/Source/cmIncludeDirectoryCommand.h
@@ -69,6 +69,8 @@ public:
     return
       "INCLUDE_DIRECTORIES(dir1 dir2 ...)";
     }
+  
+  cmTypeMacro(cmIncludeDirectoryCommand, cmCommand);
 };
 
 
diff --git a/Source/cmLibraryCommand.h b/Source/cmLibraryCommand.h
index 74957cb66..0abb2dd51 100644
--- a/Source/cmLibraryCommand.h
+++ b/Source/cmLibraryCommand.h
@@ -64,6 +64,8 @@ public:
     return
       "LIBRARY(libraryname)";
     }
+  
+  cmTypeMacro(cmLibraryCommand, cmCommand);
 };
 
 
diff --git a/Source/cmLinkDirectoriesCommand.h b/Source/cmLinkDirectoriesCommand.h
index 783c8802f..36a6ad8ee 100644
--- a/Source/cmLinkDirectoriesCommand.h
+++ b/Source/cmLinkDirectoriesCommand.h
@@ -74,6 +74,8 @@ public:
       "The directories can use built in definitions like \n"
       "CMAKE_BINARY_DIR and CMAKE_SOURCE_DIR.";
     }
+  
+  cmTypeMacro(cmLinkDirectoriesCommand, cmCommand);
 };
 
 
diff --git a/Source/cmLinkLibrariesCommand.h b/Source/cmLinkLibrariesCommand.h
index 31e931031..5f01d524a 100644
--- a/Source/cmLinkLibrariesCommand.h
+++ b/Source/cmLinkLibrariesCommand.h
@@ -76,6 +76,8 @@ public:
       "down to all other commands. The library name should be\n"
       "the same as the name used in the LIBRARY(library) command.";
     }
+  
+  cmTypeMacro(cmLinkLibrariesCommand, cmCommand);
 };
 
 
diff --git a/Source/cmProjectCommand.h b/Source/cmProjectCommand.h
index fe395b056..7c0c67377 100644
--- a/Source/cmProjectCommand.h
+++ b/Source/cmProjectCommand.h
@@ -74,6 +74,8 @@ public:
     return
       "PROJECT(projectname) Sets the name of the Microsoft workspace .dsw file. Does nothing on UNIX currently\n";
     }
+  
+  cmTypeMacro(cmProjectCommand, cmCommand);
 };
 
 
diff --git a/Source/cmSourceFilesCommand.h b/Source/cmSourceFilesCommand.h
index f53433982..6ff44b20d 100644
--- a/Source/cmSourceFilesCommand.h
+++ b/Source/cmSourceFilesCommand.h
@@ -68,6 +68,8 @@ public:
     return
       "SOURCE_FILES(file1 file2 ...)";
     }
+  
+  cmTypeMacro(cmSourceFilesCommand, cmCommand);
 };
 
 
diff --git a/Source/cmSourceFilesRequireCommand.h b/Source/cmSourceFilesRequireCommand.h
index e84c21e22..b7253b7a1 100644
--- a/Source/cmSourceFilesRequireCommand.h
+++ b/Source/cmSourceFilesRequireCommand.h
@@ -67,6 +67,8 @@ public:
     return
       "SOURCE_FILES_REQUIRE(var1 var2 ... SOURCES_BEGIN file1 file2 ...)";
     }
+  
+  cmTypeMacro(cmSourceFilesRequireCommand, cmCommand);
 };
 
 
diff --git a/Source/cmSubdirCommand.h b/Source/cmSubdirCommand.h
index 43a501e0b..fd8b346be 100644
--- a/Source/cmSubdirCommand.h
+++ b/Source/cmSubdirCommand.h
@@ -67,6 +67,8 @@ public:
       "This will cause any CMakeLists.txt files in the sub directories\n"
       "to be processed by CMake.";
     }
+  
+  cmTypeMacro(cmSubdirCommand, cmCommand);
 };
 
 
diff --git a/Source/cmTestsCommand.h b/Source/cmTestsCommand.h
index ec001b3c3..0a9fd9318 100644
--- a/Source/cmTestsCommand.h
+++ b/Source/cmTestsCommand.h
@@ -67,6 +67,8 @@ public:
     return
       "TESTS(file1 file2 ...)";
     }
+  
+  cmTypeMacro(cmTestsCommand, cmCommand);
 };
 
 
diff --git a/Source/cmUnixDefinesCommand.h b/Source/cmUnixDefinesCommand.h
index f912ff4da..595792c8b 100644
--- a/Source/cmUnixDefinesCommand.h
+++ b/Source/cmUnixDefinesCommand.h
@@ -75,6 +75,8 @@ public:
       "UNIX_DEFINES(-DFOO -DBAR)\n"
       "Add -D flags to the command line for Unix only.";
     }
+  
+  cmTypeMacro(cmUnixDefinesCommand, cmCommand);
 };
 
 
diff --git a/Source/cmUnixLibrariesCommand.h b/Source/cmUnixLibrariesCommand.h
index 80a77a482..e3c883d15 100644
--- a/Source/cmUnixLibrariesCommand.h
+++ b/Source/cmUnixLibrariesCommand.h
@@ -74,6 +74,8 @@ public:
     return
       "UNIX_LIBRARIES(library -lm ...)";
     }
+  
+  cmTypeMacro(cmUnixLibrariesCommand, cmCommand);
 };
 
 
diff --git a/Source/cmWin32DefinesCommand.h b/Source/cmWin32DefinesCommand.h
index a8e0da89f..af07265be 100644
--- a/Source/cmWin32DefinesCommand.h
+++ b/Source/cmWin32DefinesCommand.h
@@ -75,6 +75,8 @@ public:
       "WIN32_DEFINES(-DFOO -DBAR ...)\n"
       "Add -D define flags to command line for Win32 environments.";
     }
+  
+  cmTypeMacro(cmWin32DefinesCommand, cmCommand);
 };
 
 
diff --git a/Source/cmWin32LibrariesCommand.h b/Source/cmWin32LibrariesCommand.h
index 61d7b189d..02885afbb 100644
--- a/Source/cmWin32LibrariesCommand.h
+++ b/Source/cmWin32LibrariesCommand.h
@@ -74,6 +74,8 @@ public:
     return
       "WIN32_LIBRARIES(library -lm ...)";
     }
+  
+  cmTypeMacro(cmWin32LibrariesCommand, cmCommand);
 };