diff --git a/modules.yaml b/modules.yaml
index 607a824..f707d2a 100644
--- a/modules.yaml
+++ b/modules.yaml
@@ -34,6 +34,8 @@ modules:
             - src/kernel/main.cpp
             - src/kernel/memory_bootstrap.cpp
             - src/kernel/msr.cpp
+            - src/kernel/objects/handle.cpp
+            - src/kernel/objects/kobject.cpp
             - src/kernel/page_manager.cpp
             - src/kernel/pci.cpp
             - src/kernel/process.cpp
diff --git a/src/include/j6/errors.h b/src/include/j6/errors.h
new file mode 100644
index 0000000..1e1b012
--- /dev/null
+++ b/src/include/j6/errors.h
@@ -0,0 +1,16 @@
+#pragma once
+/// \file errors.h
+/// Collection of constants for the j6_status_t type
+
+#define j6_status_error				0x8000000000000000
+#define j6_err(x)					((x) | j6_status_error)
+#define j6_is_err(x)				(((x) & j6_status_error) == j6_status_error)
+
+#define j6_status_ok				0x0000
+
+#define j6_status_destroyed			0x1001
+
+#define j6_err_nyi					j6_err(0x0001)
+#define j6_err_unexpected			j6_err(0x0002)
+#define j6_err_invalid_arg			j6_err(0x0003)
+
diff --git a/src/include/j6/signals.h b/src/include/j6/signals.h
new file mode 100644
index 0000000..0f27c2f
--- /dev/null
+++ b/src/include/j6/signals.h
@@ -0,0 +1,18 @@
+#pragma once
+/// \file signals.h
+/// Collection of constants for the j6_signal_t type
+
+// Signals 0-7 are common to all types
+#define j6_signal_no_handles		(1 << 0)
+
+// Signals 8-15 are user-defined signals
+#define j6_signal_user0				(1 << 8)
+#define j6_signal_user1				(1 << 9)
+#define j6_signal_user2				(1 << 10)
+#define j6_signal_user3				(1 << 11)
+#define j6_signal_user4				(1 << 12)
+#define j6_signal_user5				(1 << 13)
+#define j6_signal_user6				(1 << 14)
+#define j6_signal_user7				(1 << 15)
+
+// All other signals are type-specific
diff --git a/src/include/j6/types.h b/src/include/j6/types.h
new file mode 100644
index 0000000..ccff446
--- /dev/null
+++ b/src/include/j6/types.h
@@ -0,0 +1,20 @@
+#pragma once
+/// \file types.h
+/// Basic kernel types exposed to userspace
+
+#include <stdint.h>
+
+/// All interactable kernel objects have a uniqe kernel object id
+typedef uint64_t j6_koid_t;
+
+/// Syscalls return status as this type
+typedef uint32_t j6_status_t;
+
+/// Handles are references and capabilities to other objects
+typedef uint32_t j6_handle_t;
+
+/// Some objects have signals, which are a bitmap of 64 possible signals
+typedef uint64_t j6_signal_t;
+
+/// The rights of a handle/capability are a bitmap of 64 possible rights
+typedef uint64_t j6_rights_t;
diff --git a/src/include/log_areas.inc b/src/include/log_areas.inc
index c63ce77..15f8787 100644
--- a/src/include/log_areas.inc
+++ b/src/include/log_areas.inc
@@ -8,3 +8,4 @@ LOG(task,   info);
 LOG(boot,   debug);
 LOG(syscall,debug);
 LOG(vmem,   debug);
+LOG(objs,   debug);
diff --git a/src/kernel/main.cpp b/src/kernel/main.cpp
index a2a1516..574a41c 100644
--- a/src/kernel/main.cpp
+++ b/src/kernel/main.cpp
@@ -1,6 +1,8 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include "j6/signals.h"
+
 #include "initrd/initrd.h"
 #include "kutil/assert.h"
 #include "kutil/heap_allocator.h"
@@ -16,6 +18,8 @@
 #include "kernel_args.h"
 #include "kernel_memory.h"
 #include "log.h"
+#include "objects/event.h"
+#include "objects/handle.h"
 #include "page_manager.h"
 #include "scheduler.h"
 #include "serial.h"
@@ -30,6 +34,26 @@ extern void __kernel_assert(const char *, unsigned, const char *);
 
 extern kutil::heap_allocator g_kernel_heap;
 
+class test_observer :
+	public kobject::observer
+{
+public:
+	test_observer(const char *name) : m_name(name) {}
+
+	virtual bool on_signals_changed(
+			kobject *obj,
+			j6_signal_t s,
+			j6_signal_t ds,
+			j6_status_t result)
+	{
+		log::info(logs::objs, "  %s: Signals %016lx changed, object %p, result %016lx",
+				m_name, ds, obj, result);
+		return false;
+	}
+
+	const char *m_name;
+};
+
 void
 init_console()
 {
@@ -143,5 +167,20 @@ kernel_main(kernel_args *header)
 			sched->load_process(f.name(), f.data(), f.size());
 	}
 
+	log::info(logs::objs, "Testing object system:");
+
+	test_observer obs1("event");
+	test_observer obs2("no handles");
+	{
+		event e;
+
+		e.register_signal_observer(&obs1, j6_signal_user0);
+		e.register_signal_observer(&obs2, j6_signal_no_handles);
+
+		e.assert_signal(j6_signal_user0);
+
+		handle h(1, 0, &e);
+	}
+
 	sched->start();
 }
diff --git a/src/kernel/objects/event.h b/src/kernel/objects/event.h
new file mode 100644
index 0000000..fe5ff64
--- /dev/null
+++ b/src/kernel/objects/event.h
@@ -0,0 +1,15 @@
+#pragma once
+/// \file event.h
+/// Definition of event kobject types
+
+#include "objects/kobject.h"
+
+class event :
+	public kobject
+{
+public:
+	static constexpr type type_id = type::event;
+
+	event() :
+		kobject(type_id) {}
+};
diff --git a/src/kernel/objects/handle.cpp b/src/kernel/objects/handle.cpp
new file mode 100644
index 0000000..37991a7
--- /dev/null
+++ b/src/kernel/objects/handle.cpp
@@ -0,0 +1,26 @@
+#include "objects/handle.h"
+
+handle::handle(handle&& other) :
+	m_owner(other.m_owner),
+	m_object(other.m_object),
+	m_rights(other.m_rights)
+{
+	other.m_owner = 0;
+	other.m_object = nullptr;
+	other.m_rights = 0;
+}
+
+handle::handle(j6_koid_t owner, j6_rights_t rights, kobject *obj) :
+	m_owner(owner),
+	m_object(obj),
+	m_rights(rights)
+{
+	if (m_object)
+		m_object->handle_retain();
+}
+
+handle::~handle()
+{
+	if (m_object)
+		m_object->handle_release();
+}
diff --git a/src/kernel/objects/handle.h b/src/kernel/objects/handle.h
new file mode 100644
index 0000000..c8a77a7
--- /dev/null
+++ b/src/kernel/objects/handle.h
@@ -0,0 +1,30 @@
+#pragma once
+/// \file handle.h
+/// Defines types for user handles to kernel objects
+
+#include "j6/types.h"
+#include "objects/kobject.h"
+
+class handle
+{
+public:
+	/// Move constructor. Takes ownership of the object from other.
+	handle(handle&& other);
+
+	/// Constructor.
+	/// \arg owner   koid of the process that has this handle
+	/// \arg rights  access rights this handle has over the object
+	/// \arg obj     the object held
+	handle(j6_koid_t owner, j6_rights_t rights, kobject *obj);
+
+	~handle();
+
+	handle() = delete;
+	handle(const handle &other) = delete;
+	handle & operator=(const handle& other) = delete;
+
+private:
+	j6_koid_t m_owner;
+	kobject *m_object;
+	j6_rights_t m_rights;
+};
diff --git a/src/kernel/objects/kobject.cpp b/src/kernel/objects/kobject.cpp
new file mode 100644
index 0000000..64bc8af
--- /dev/null
+++ b/src/kernel/objects/kobject.cpp
@@ -0,0 +1,98 @@
+#include "j6/errors.h"
+#include "j6/signals.h"
+#include "j6/types.h"
+#include "kutil/heap_allocator.h"
+#include "objects/kobject.h"
+
+extern kutil::heap_allocator g_kernel_heap;
+
+// TODO: per-cpu this?
+static j6_koid_t next_koid;
+
+kobject::kobject(type t, j6_signal_t signals) :
+	m_koid(koid_generate(t)),
+	m_signals(signals),
+	m_observers(g_kernel_heap),
+	m_handle_count(0)
+{}
+
+kobject::~kobject()
+{
+	notify_signal_observers(0, j6_status_destroyed);
+}
+
+j6_koid_t
+kobject::koid_generate(type t)
+{
+	return (static_cast<uint64_t>(t) << 48) | next_koid++;
+}
+
+kobject::type
+kobject::koid_type(j6_koid_t koid)
+{
+	return static_cast<type>((koid >> 48) & 0xffffull);
+}
+
+void
+kobject::assert_signal(j6_signal_t s)
+{
+	m_signals |= s;
+	notify_signal_observers(s);
+}
+
+void
+kobject::deassert_signal(j6_signal_t s)
+{
+	m_signals &= ~s;
+	notify_signal_observers(s);
+}
+
+void
+kobject::register_signal_observer(observer *object, j6_signal_t s)
+{
+	m_observers.emplace(object, s);
+}
+
+void
+kobject::deregister_signal_observer(observer *object)
+{
+	for (size_t i = 0; i < m_observers.count(); ++i) {
+		auto &reg = m_observers[i];
+		if (reg.object != object) continue;
+
+		reg = m_observers[m_observers.count() - 1];
+		m_observers.remove();
+		break;
+	}
+}
+
+void
+kobject::notify_signal_observers(j6_signal_t mask, j6_status_t result)
+{
+	for (auto &reg : m_observers) {
+		if (mask == 0 || (reg.signals & mask) != 0) {
+			if (!reg.object->on_signals_changed(this, m_signals, mask, result))
+				reg.object = nullptr;
+		}
+	}
+
+	// Compact the observer list
+	long last = m_observers.count() - 1;
+	while (m_observers[last].object == nullptr && last >= 0) last--;
+
+	for (long i = 0; i < long(m_observers.count()) && i < last; ++i) {
+		auto &reg = m_observers[i];
+		if (reg.object != nullptr) continue;
+		reg = m_observers[last--];
+
+		while (m_observers[last].object == nullptr && last >= i) last--;
+	}
+
+	m_observers.set_size(last + 1);
+}
+
+void
+kobject::on_no_handles()
+{
+	assert_signal(j6_signal_no_handles);
+}
diff --git a/src/kernel/objects/kobject.h b/src/kernel/objects/kobject.h
new file mode 100644
index 0000000..d8a8b39
--- /dev/null
+++ b/src/kernel/objects/kobject.h
@@ -0,0 +1,110 @@
+#pragma once
+/// \file kobject.h
+/// Definition of base type for user-interactable kernel objects
+
+#include "j6/errors.h"
+#include "j6/types.h"
+#include "kutil/vector.h"
+
+/// Base type for all user-interactable kernel objects
+class kobject
+{
+public:
+	/// Types of kernel objects.
+	enum class type : uint16_t
+	{
+		none,
+
+		event,
+		eventpair,
+
+		vms,
+		vmo,
+
+		job,
+		process,
+		thread,
+	};
+
+	kobject(type t, j6_signal_t signals = 0ull);
+	virtual ~kobject();
+
+	/// Generate a new koid for a given type
+	/// \arg t    The object type
+	/// \returns  A new unique koid
+	static j6_koid_t koid_generate(type t);
+
+	/// Get the kobject type from a given koid
+	/// \arg koid  An existing koid
+	/// \returns   The object type for the koid
+	static type koid_type(j6_koid_t koid);
+
+	/// Set the given signals active on this object
+	/// \arg s  The set of signals to assert
+	void assert_signal(j6_signal_t s);
+
+	/// Clear the given signals on this object
+	/// \arg s  The set of signals to deassert
+	void deassert_signal(j6_signal_t s);
+
+	class observer
+	{
+	public:
+		/// Callback for when signals change.
+		/// \arg obj     The object triggering the callback
+		/// \arg s       The current state of obj's signals
+		/// \arg ds      Which signals caused the callback
+		/// \arg result  Status code for this notification
+		/// \returns     True if this object wants to keep watching signals
+		virtual bool on_signals_changed(
+				kobject *obj,
+				j6_signal_t s,
+				j6_signal_t ds,
+				j6_status_t result) = 0;
+	};
+
+	/// Register a signal observer
+	/// \arg object  The observer
+	/// \arg s       The signals the object wants notifiations for
+	void register_signal_observer(observer *object, j6_signal_t s);
+
+	/// Deegister a signal observer
+	/// \arg object  The observer
+	void deregister_signal_observer(observer *object);
+
+	/// Increment the handle refcount
+	inline void handle_retain() { ++m_handle_count; }
+
+	/// Decrement the handle refcount
+	inline void handle_release() {
+		if (--m_handle_count == 0) on_no_handles();
+	}
+
+protected:
+	kobject() = delete;
+	kobject(const kobject &other) = delete;
+	kobject(const kobject &&other) = delete;
+
+	/// Notifiy observers of this object
+	/// \arg mask    The signals that triggered this call. If 0, notify all observers.
+	/// \arg result  The result to pass to the observers
+	void notify_signal_observers(j6_signal_t mask, j6_status_t result = j6_status_ok);
+
+	/// Interface for subclasses to handle when all handles are closed. Subclasses
+	/// should either call the base version, or assert j6_signal_no_handles.
+	virtual void on_no_handles();
+
+	j6_koid_t m_koid;
+	j6_signal_t m_signals;
+	uint16_t m_handle_count;
+
+	struct observer_registration
+	{
+		observer_registration(observer* o = nullptr, j6_signal_t s = 0) :
+			object(o), signals(s) {}
+
+		observer *object;
+		j6_signal_t signals;
+	};
+	kutil::vector<observer_registration> m_observers;
+};
diff --git a/src/libraries/kutil/include/kutil/vector.h b/src/libraries/kutil/include/kutil/vector.h
index e963afc..8522cd8 100644
--- a/src/libraries/kutil/include/kutil/vector.h
+++ b/src/libraries/kutil/include/kutil/vector.h
@@ -117,12 +117,14 @@ public:
 		m_elements[m_size].~T();
 	}
 
-	/// Set the size of the array. Any new items are default
-	/// constructed. The array is realloced if needed.
+	/// Set the size of the array. Any new items are default constructed.
+	/// Any items past the end are deleted. The array is realloced if needed.
 	/// \arg size  The new size
 	void set_size(size_t size)
 	{
 		ensure_capacity(size);
+		for (size_t i = size; i < m_size; ++i)
+			m_elements[i].~T();
 		for (size_t i = m_size; i < size; ++i)
 			new (&m_elements[i]) T;
 		m_size = size;