diff --git a/client/hostinfo_unix.C b/client/hostinfo_unix.C
index 7313974e2b..d5a6cdf3d0 100644
--- a/client/hostinfo_unix.C
+++ b/client/hostinfo_unix.C
@@ -71,6 +71,10 @@
 
 using std::string;
 
+#ifdef __APPLE__
+NXEventHandle gEventHandle;
+#endif  // __APPLE__
+
 // anyone know how to see if this host has physical network connection?
 //
 int get_connected_state() {
@@ -580,6 +584,10 @@ bool HOST_INFO::users_idle(bool check_all_logins, double idle_time_to_run) {
 #ifdef HAVE__DEV_TTY1
         && (check_all_logins || all_tty_idle(idle_time, device_tty, '1', 7))
 #endif
+#ifdef __APPLE__
+        && (NXIdleTime(gEventHandle) > (60 * idle_time_to_run))
+#endif  // __APPLE__
+
         ;
 }
 
diff --git a/client/main.C b/client/main.C
index 5264bcd62a..cfdacb3c83 100644
--- a/client/main.C
+++ b/client/main.C
@@ -140,6 +140,9 @@ void show_message(PROJECT *p, char* msg, int priority) {
 // and create an account file
 //
 int add_new_project() {
+#if defined(__WXMAC__)    // If we have a GUI BOINC Manager
+    return 0;
+#else
     PROJECT project;
 
     printf("Enter the URL of the project: ");
@@ -158,6 +161,7 @@ int add_new_project() {
 
     project.tentative = true;
     return project.write_account_file();
+#endif
 }
 
 #ifdef WIN32
@@ -418,6 +422,12 @@ int main(int argc, char** argv) {
         retval = boinc_main_loop();
     }
 #else
+
+#ifdef __APPLE__
+        // Initialize Mac OS X idle time measurement / idle detection
+        gEventHandle = NXOpenEventStatus();
+#endif  // __APPLE__
+
     retval = boinc_main_loop();
 #endif
 
diff --git a/client/net_xfer.C b/client/net_xfer.C
index 7a7e95da74..aa7cf56912 100644
--- a/client/net_xfer.C
+++ b/client/net_xfer.C
@@ -68,6 +68,26 @@ using std::vector;
 // in this many seconds, error out
 #define NET_XFER_TIMEOUT    600
 
+static void boinc_close_socket(int sock) {
+#ifdef _WIN32
+    closesocket(sock);
+#else
+    close(sock);
+#endif
+}
+
+int get_socket_error(int fd) {
+    socklen_t intsize = sizeof(int);
+    int n;
+#ifdef WIN32
+    getsockopt(fd, SOL_SOCKET, SO_ERROR, (char *)&n, &intsize);
+#elif __APPLE__
+    getsockopt(fd, SOL_SOCKET, SO_ERROR, &n, (int *)&intsize);
+#else
+    getsockopt(fd, SOL_SOCKET, SO_ERROR, (void*)&n, &intsize);
+#endif
+    return n;
+}
 
 int NET_XFER::get_ip_addr(int &ip_addr) {
 
diff --git a/clientgui/BOINCGUIApp.cpp b/clientgui/BOINCGUIApp.cpp
index bb8ad5ef41..4d8435aae8 100644
--- a/clientgui/BOINCGUIApp.cpp
+++ b/clientgui/BOINCGUIApp.cpp
@@ -34,6 +34,9 @@ typedef void (CALLBACK* IdleTrackerTerm)();
 typedef DWORD (CALLBACK* IdleTrackerGetIdleTickCount)();
 #endif
 
+#ifdef __WXMAC__
+#include <Carbon/Carbon.h>
+#endif
 
 IMPLEMENT_APP(CBOINCGUIApp)
 IMPLEMENT_DYNAMIC_CLASS(CBOINCGUIApp, wxApp)
@@ -304,6 +307,43 @@ void CBOINCGUIApp::StartupBOINCCore()
 
 #endif
 
+#ifdef __WXMAC__
+
+        {
+            wxChar buf[1024];
+            bool success;
+            ProcessSerialNumber ourPSN;
+            FSRef ourFSRef;
+            OSErr err;
+
+            // Set the current directory ahead of the application launch so the core
+            //   client can find its files
+            wxExpandPath(buf, "~/Library/Application Support");
+            strDirectory = wxT(buf);
+            success = ::wxSetWorkingDirectory( strDirectory );
+            if (success)            // If SetWD failed, don't create a directory in wrong place
+                success = wxMkdir( wxT("BOINC Data"), 0777);    // Does nothing if dir exists
+            strDirectory += wxT("/BOINC Data");
+            success = ::wxSetWorkingDirectory( strDirectory );
+//          wxChar *wd = wxGetWorkingDirectory(buf, 1000);  // For debugging
+            // Get the full path to core client inside this application's bundle
+            err = GetCurrentProcess (&ourPSN);
+            if (err == noErr)
+                err = GetProcessBundleLocation(&ourPSN, &ourFSRef);
+            if (err == noErr)
+                err = FSRefMakePath (&ourFSRef, (UInt8*)buf, sizeof(buf));
+            if (err == noErr)
+            {
+                strExecute = wxT("\"");            
+                strExecute += wxT(buf);
+                strExecute += wxT("/Contents/Resources/boinc_client\" -redirectio");
+            }
+            else
+                buf[0] = '\0';
+        }
+
+#else   // ! __WXMAC__
+
         // We are only interested in the path component of the fully qualified path.
         wxFileName::SplitPath( szExecutableDirectory, &strDirectory, NULL, NULL );
 
@@ -311,6 +351,8 @@ void CBOINCGUIApp::StartupBOINCCore()
         //   client can find its files
         ::wxSetWorkingDirectory( strDirectory );
 
+#endif  // ! __WXMAC__
+
 #ifdef __WXMSW__
 
         // Append boinc.exe to the end of the strExecute string and get ready to rock
@@ -347,11 +389,16 @@ void CBOINCGUIApp::StartupBOINCCore()
 
 #else
 
+#ifndef __WXMAC__
+
         // Append boinc.exe to the end of the strExecute string and get ready to rock
         strExecute += wxT("/boinc");
+        
+#endif  // ! __WXMAC__
+
         m_lBOINCCoreProcessId = ::wxExecute( strExecute );
 
-#endif
+#endif  // ! __WXMSW__
 
         if ( 0 != m_lBOINCCoreProcessId )
             m_bBOINCStartedByManager = true;
diff --git a/lib/hostinfo.h b/lib/hostinfo.h
index d8b0186df3..8aacd4d665 100644
--- a/lib/hostinfo.h
+++ b/lib/hostinfo.h
@@ -74,4 +74,19 @@ struct HOST_INFO {
     extern HINSTANCE g_hIdleDetectionDll;       // handle to DLL for user idle
 #endif
 
+#ifdef __APPLE__
+#ifdef __cplusplus
+extern "C" {
+#endif
+#include <mach/port.h>
+typedef mach_port_t NXEventHandle;
+NXEventHandle NXOpenEventStatus(void);
+extern double NXIdleTime(NXEventHandle handle);
+#ifdef __cplusplus
+}	// extern "C"
+#endif
+
+extern NXEventHandle gEventHandle;
+#endif
+
 #endif
diff --git a/mac_build/boinc.pbproj.zip b/mac_build/boinc.pbproj.zip
new file mode 100644
index 0000000000..95fcf744fe
Binary files /dev/null and b/mac_build/boinc.pbproj.zip differ