diff --git a/mailnews/addrbook/build/nsAbFactory.cpp b/mailnews/addrbook/build/nsAbFactory.cpp
index dfe6e710ef1..5ca628537b4 100644
--- a/mailnews/addrbook/build/nsAbFactory.cpp
+++ b/mailnews/addrbook/build/nsAbFactory.cpp
@@ -64,7 +64,9 @@ static nsModuleComponentInfo components[] =
   { "Address Book",
     NS_ADDRESSBOOK_CID,
     NS_ADDRESSBOOK_PROGID,
-    nsAddressBookConstructor },
+    nsAddressBookConstructor,
+    nsAddressBook::RegisterProc,
+    nsAddressBook::UnregisterProc },	
   { "Address Book Directory Datasource",
     NS_ABDIRECTORYDATASOURCE_CID,
     NS_ABDIRECTORYDATASOURCE_PROGID,
diff --git a/mailnews/addrbook/src/nsAddressBook.cpp b/mailnews/addrbook/src/nsAddressBook.cpp
index d8548d5261d..39441432cbb 100644
--- a/mailnews/addrbook/src/nsAddressBook.cpp
+++ b/mailnews/addrbook/src/nsAddressBook.cpp
@@ -48,7 +48,8 @@
 #include "nsIDOMWindow.h"
 #include "nsIContentViewer.h"
 #include "nsIContentViewerFile.h"
-
+#include "nsXPIDLString.h"
+#include "nsICategoryManager.h"
 
 static NS_DEFINE_CID(kRDFServiceCID, NS_RDFSERVICE_CID);
 static NS_DEFINE_IID(kAppShellServiceCID, NS_APPSHELL_SERVICE_CID);
@@ -116,7 +117,10 @@ nsAddressBook::~nsAddressBook()
 {
 }
 
-NS_IMPL_ISUPPORTS(nsAddressBook, NS_GET_IID(nsIAddressBook));
+NS_IMPL_THREADSAFE_ADDREF(nsAddressBook);
+NS_IMPL_THREADSAFE_RELEASE(nsAddressBook);
+
+NS_IMPL_QUERY_INTERFACE2(nsAddressBook, nsIAddressBook, nsICmdLineHandler);
 
 //
 // nsIAddressBook
@@ -1266,3 +1270,77 @@ NS_IMETHODIMP nsAddressBook::ImportAddressBook()
 	return rv;
 }
 
+
+NS_IMETHODIMP
+nsAddressBook::GetCommandLineArgument(char **aCommandLineArgument)
+{
+    if (!aCommandLineArgument) return NS_ERROR_FAILURE;
+
+    *aCommandLineArgument = PL_strdup("-addressbook");
+
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+nsAddressBook::GetPrefNameForStartup(char **aPrefNameForStartup)
+{
+    if (!aPrefNameForStartup) return NS_ERROR_FAILURE;
+
+    *aPrefNameForStartup = PL_strdup("general.startup.addressbook");
+
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+nsAddressBook::GetChromeUrlForTask(char **aChromeUrlForTask)
+{
+    if (!aChromeUrlForTask) return NS_ERROR_FAILURE;
+
+    *aChromeUrlForTask = PL_strdup("chrome://addressbook/content/");
+
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+nsAddressBook::GetHelpText(char **aHelpText)
+{
+    if (!aHelpText) return NS_ERROR_FAILURE;
+
+    *aHelpText = PL_strdup("Start with the addressbook.");
+
+    return NS_OK;
+}
+
+NS_METHOD nsAddressBook::RegisterProc(nsIComponentManager *aCompMgr,
+                                           nsIFile *aPath,
+                                           const char *registryLocation,
+                                           const char *componentType)
+
+{
+    // Register ourselves into the COMMAND_LINE_ARGUMENT_HANDLERS
+    nsresult rv;
+    nsCOMPtr<nsICategoryManager> catman = do_GetService("mozilla.categorymanager.1", &rv);
+    if (NS_FAILED(rv)) return rv;
+
+    nsXPIDLCString prevEntry;
+    rv = catman->AddCategoryEntry(COMMAND_LINE_ARGUMENT_HANDLERS, NS_ADDRESSBOOK_PROGID, "Addressbook Cmd Line Handler", PR_TRUE, PR_TRUE, getter_Copies(prevEntry));
+
+	return NS_OK;
+}
+
+NS_METHOD nsAddressBook::UnregisterProc(nsIComponentManager *aCompMgr,
+                                             nsIFile *aPath,
+                                             const char *registryLocation)
+{
+    nsresult rv;
+
+
+    nsCOMPtr<nsICategoryManager> catman = do_GetService("mozilla.categorymanager.1", &rv);
+    if (NS_FAILED(rv)) return rv;
+
+    nsXPIDLCString prevEntry;
+    rv = catman->DeleteCategoryEntry(COMMAND_LINE_ARGUMENT_HANDLERS, NS_ADDRESSBOOK_PROGID, PR_TRUE, getter_Copies(prevEntry));
+
+    // Return value is not used from this function.
+    return NS_OK;
+}
diff --git a/mailnews/addrbook/src/nsAddressBook.h b/mailnews/addrbook/src/nsAddressBook.h
index 7a26702963d..873da3ad7a6 100644
--- a/mailnews/addrbook/src/nsAddressBook.h
+++ b/mailnews/addrbook/src/nsAddressBook.h
@@ -30,13 +30,15 @@
 #include "nsIWebShell.h"
 #include "nsIScriptGlobalObject.h"
 #include "nsIFileSpecWithUI.h"
-
+#include "nsICmdLineHandler.h"
+#include "nsIComponentManager.h"
+#include "nsIFileSpec.h"
 
 #define NC_RDF_NEWABCARD			"http://home.netscape.com/NC-rdf#NewCard"
 #define NC_RDF_DELETE				"http://home.netscape.com/NC-rdf#Delete"
 #define NC_RDF_NEWDIRECTORY			"http://home.netscape.com/NC-rdf#NewDirectory"
 
-class nsAddressBook : public nsIAddressBook
+class nsAddressBook : public nsIAddressBook, nsICmdLineHandler
 {
   
 public:
@@ -44,7 +46,17 @@ public:
 	virtual ~nsAddressBook();
 
 	NS_DECL_ISUPPORTS
-    NS_DECL_NSIADDRESSBOOK
+ 	NS_DECL_NSIADDRESSBOOK
+	NS_DECL_NSICMDLINEHANDLER
+
+  static NS_METHOD RegisterProc(nsIComponentManager *aCompMgr,
+                                nsIFile *aPath,
+                                const char *registryLocation,
+                                const char *componentType);
+
+  static NS_METHOD UnregisterProc(nsIComponentManager *aCompMgr,
+                                  nsIFile *aPath,
+                                  const char *registryLocation);
 
 protected:
 	nsresult DoCommand(nsIRDFCompositeDataSource *db, char * command, nsISupportsArray *srcArray,