diff --git a/librecomp/CMakeLists.txt b/librecomp/CMakeLists.txt
index 4db1505..fcc3337 100644
--- a/librecomp/CMakeLists.txt
+++ b/librecomp/CMakeLists.txt
@@ -12,6 +12,7 @@ add_library(librecomp STATIC
     "${CMAKE_CURRENT_SOURCE_DIR}/src/dp.cpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/src/eep.cpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/src/euc-jp.cpp"
+    "${CMAKE_CURRENT_SOURCE_DIR}/src/extensions.cpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/src/files.cpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/src/flash.cpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/src/heap.cpp"
diff --git a/librecomp/src/extensions.cpp b/librecomp/src/extensions.cpp
new file mode 100644
index 0000000..33174c5
--- /dev/null
+++ b/librecomp/src/extensions.cpp
@@ -0,0 +1,11 @@
+#include "recomp.h"
+#include "ultramodern/extensions.h"
+#include "librecomp/helpers.hpp"
+
+extern "C" void osExQueueDisplaylistEvent_recomp(uint8_t* rdram, recomp_context* ctx) {
+    PTR(OSMesgQueue) mq   = _arg<0, PTR(OSMesgQueue)>(rdram, ctx);
+    OSMesg mesg           = _arg<1, OSMesg>(rdram, ctx);
+    PTR(void) displaylist = _arg<2, PTR(void)>(rdram, ctx);
+    u32 event_type        = _arg<3, u32>(rdram, ctx);
+    osExQueueDisplaylistEvent(mq, mesg, displaylist, event_type);
+}
diff --git a/ultramodern/CMakeLists.txt b/ultramodern/CMakeLists.txt
index 90ac35a..5593172 100644
--- a/ultramodern/CMakeLists.txt
+++ b/ultramodern/CMakeLists.txt
@@ -9,6 +9,7 @@ add_library(ultramodern STATIC
     "${CMAKE_CURRENT_SOURCE_DIR}/src/audio.cpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/src/error_handling.cpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/src/events.cpp"
+    "${CMAKE_CURRENT_SOURCE_DIR}/src/extensions.cpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/src/input.cpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/src/mesgqueue.cpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/src/misc_ultra.cpp"
diff --git a/ultramodern/include/ultramodern/extensions.h b/ultramodern/include/ultramodern/extensions.h
new file mode 100644
index 0000000..0b9095b
--- /dev/null
+++ b/ultramodern/include/ultramodern/extensions.h
@@ -0,0 +1,48 @@
+#ifndef __ULTRAMODERN_EXTENSIONS_H__
+#define __ULTRAMODERN_EXTENSIONS_H__
+
+#if defined(mips) // Patch compilation
+#include <ultra64.h>
+#else
+#include "ultramodern/ultra64.h"
+#endif
+
+#ifndef PTR
+#define PTR(x) x*
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef enum {
+    // Triggers when a displaylist has been submitted to the renderer.
+    OS_EX_DISPLAYLIST_EVENT_SUBMITTED,
+    // Triggers when a displaylist has been fully parsed by the renderer. This includes any referenced data, such
+    // as vertices, matrices, and textures.
+    OS_EX_DISPLAYLIST_EVENT_PARSED,
+    // Triggers when rendering of a displaylist has been completed by the renderer. This only includes the
+    // rendering pass that produces an image in RAM, not the high res output images that get presented to the user.
+    OS_EX_DISPLAYLIST_EVENT_COMPLETED
+} DisplaylistEventType;
+
+// Queues a one-time message to be sent the next time the given event type occurs for the given displaylist.
+// This allows easier detection of displaylist events without needing to patch a game's scheduler.
+// The event will be cleared after it occurs.
+// event_type must be a member of the DisplaylistEventType enum.
+void osExQueueDisplaylistEvent(PTR(OSMesgQueue) mq, OSMesg mesg, PTR(void) displaylist, u32 event_type);
+
+#ifdef __cplusplus
+}
+
+namespace ultramodern {
+    namespace extensions {
+        void on_displaylist_submitted(PTR(u64) displaylist);
+        void on_displaylist_parsed(PTR(u64) displaylist);
+        void on_displaylist_completed(PTR(u64) displaylist);
+    }
+}
+
+#endif
+
+#endif
diff --git a/ultramodern/src/events.cpp b/ultramodern/src/events.cpp
index 2aeb93a..1cd7907 100644
--- a/ultramodern/src/events.cpp
+++ b/ultramodern/src/events.cpp
@@ -13,6 +13,7 @@
 
 #include "ultramodern/ultra64.h"
 #include "ultramodern/ultramodern.hpp"
+#include "ultramodern/extensions.h"
 
 #include "ultramodern/rsp.hpp"
 #include "ultramodern/renderer_context.hpp"
@@ -364,10 +365,17 @@ void gfx_thread_func(uint8_t* rdram, moodycamel::LightweightSemaphore* thread_re
                 sp_complete();
                 ultramodern::measure_input_latency();
 
+                PTR(u64) displaylist = task_action->task.t.data_ptr;
+                ultramodern::extensions::on_displaylist_submitted(displaylist);
+
                 [[maybe_unused]] auto renderer_start = std::chrono::high_resolution_clock::now();
                 renderer_context->send_dl(&task_action->task);
                 [[maybe_unused]] auto renderer_end = std::chrono::high_resolution_clock::now();
+
                 dp_complete();
+                // TODO hook the parsed event up to the actual parsing point when a callback is added to RT64.
+                ultramodern::extensions::on_displaylist_parsed(displaylist);
+                ultramodern::extensions::on_displaylist_completed(displaylist);
                 // printf("Renderer ProcessDList time: %d us\n", static_cast<u32>(std::chrono::duration_cast<std::chrono::microseconds>(renderer_end - renderer_start).count()));
             }
             else if (const auto* screen_update_action = std::get_if<ScreenUpdateAction>(&action)) {
diff --git a/ultramodern/src/extensions.cpp b/ultramodern/src/extensions.cpp
new file mode 100644
index 0000000..b0f4dff
--- /dev/null
+++ b/ultramodern/src/extensions.cpp
@@ -0,0 +1,60 @@
+#include <mutex>
+#include <vector>
+
+#include "ultramodern/extensions.h"
+#include "ultramodern/ultramodern.hpp"
+
+struct DLEvent {
+    PTR(OSMesgQueue) mq;
+    OSMesg mesg;
+    PTR(void) displaylist;
+    u32 event_type;
+};
+
+struct {
+    struct {
+        std::mutex dl_event_mutex;
+        std::vector<DLEvent> pending_events;
+    } dl_events;
+} extension_state;
+
+extern "C" void osExQueueDisplaylistEvent(PTR(OSMesgQueue) mq, OSMesg mesg, PTR(void) displaylist, u32 event_type) {
+    std::lock_guard lock{ extension_state.dl_events.dl_event_mutex };
+
+    assert(
+        event_type == OS_EX_DISPLAYLIST_EVENT_SUBMITTED || 
+        event_type == OS_EX_DISPLAYLIST_EVENT_PARSED || 
+        event_type == OS_EX_DISPLAYLIST_EVENT_COMPLETED);
+    
+    extension_state.dl_events.pending_events.emplace_back(
+        DLEvent{ mq, mesg, displaylist, event_type }
+    );
+}
+
+void dispatch_displaylist_events(PTR(void) displaylist, u32 event_type) {
+    std::lock_guard lock{ extension_state.dl_events.dl_event_mutex };
+
+    // Check every pending DL event to see if they match this displaylist and event type.
+    for (auto iter = extension_state.dl_events.pending_events.begin(); iter != extension_state.dl_events.pending_events.end(); ) {
+        if (iter->displaylist == displaylist && iter->event_type == event_type) {
+            // Send the provided message to the corresponding message queue for this event, then remove this event from the queue.
+            ultramodern::enqueue_external_message(iter->mq, iter->mesg, false, true);
+            iter = extension_state.dl_events.pending_events.erase(iter);
+        }
+        else {
+            ++iter;
+        }
+    }
+}
+
+void ultramodern::extensions::on_displaylist_submitted(PTR(void) displaylist) {
+    dispatch_displaylist_events(displaylist, OS_EX_DISPLAYLIST_EVENT_SUBMITTED);
+}
+
+void ultramodern::extensions::on_displaylist_parsed(PTR(void) displaylist) {
+    dispatch_displaylist_events(displaylist, OS_EX_DISPLAYLIST_EVENT_PARSED);
+}
+
+void ultramodern::extensions::on_displaylist_completed(PTR(void) displaylist) {
+    dispatch_displaylist_events(displaylist, OS_EX_DISPLAYLIST_EVENT_COMPLETED);
+}