diff --git a/include/ck_barrier.h b/include/ck_barrier.h
index ac4dc27..dd673db 100644
--- a/include/ck_barrier.h
+++ b/include/ck_barrier.h
@@ -1,5 +1,6 @@
 /*
  * Copyright 2011 Samy Al Bahra.
+ * Copyright 2011 David Joseph.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -29,6 +30,10 @@
 
 #include <ck_cc.h>
 #include <ck_pr.h>
+#include <ck_spinlock.h>
+
+#ifndef CK_BARRIER_CENTRALIZED
+#define CK_BARRIER_CENTRALIZED
 
 struct ck_barrier_centralized {
 	unsigned int value;
@@ -65,4 +70,185 @@ ck_barrier_centralized(struct ck_barrier_centralized *barrier,
 	return;
 }
 
+#endif /* CK_BARRIER_CENTRALIZED */
+
+#ifndef CK_BARRIER_COMBINING
+#define CK_BARRIER_COMBINING
+
+struct ck_barrier_combining_entry {
+	unsigned int k;
+	unsigned int count;
+	unsigned int sense;
+	struct ck_barrier_combining_entry *parent;
+	struct ck_barrier_combining_entry *lchild;
+	struct ck_barrier_combining_entry *rchild;
+	struct ck_barrier_combining_entry *next;
+};
+
+typedef struct ck_barrier_combining_entry ck_barrier_combining_entry_t;
+
+struct ck_barrier_combining_state {
+	unsigned int sense;
+};
+
+typedef struct ck_barrier_combining_state ck_barrier_combining_state_t;
+
+#define CK_BARRIER_COMBINING_STATE_INITIALIZER {~0}
+
+struct ck_barrier_combining {
+	struct ck_barrier_combining_entry *root;
+	ck_spinlock_cas_t mutex;
+};
+
+typedef struct ck_barrier_combining ck_barrier_combining_t;
+
+struct ck_barrier_ct_queue {
+	struct ck_barrier_combining_entry *head;
+	struct ck_barrier_combining_entry *tail;
+};
+
+CK_CC_INLINE static void
+ck_barrier_ct_queue_init(struct ck_barrier_ct_queue *queue)
+{
+	queue->head = queue->tail = NULL;
+	return;
+}
+
+CK_CC_INLINE static void
+ck_barrier_ct_queue_enqueue(struct ck_barrier_ct_queue *queue,
+			    struct ck_barrier_combining_entry *node_value)
+{
+	node_value->next = NULL;
+
+	if (queue->head == NULL) {
+		queue->head = queue->tail = node_value;
+
+		return;
+	}
+
+	queue->tail->next = node_value;
+	queue->tail = node_value;
+
+	return;
+}
+
+CK_CC_INLINE static struct ck_barrier_combining_entry *
+ck_barrier_ct_queue_dequeue(struct ck_barrier_ct_queue *queue)
+{
+	struct ck_barrier_combining_entry *front = NULL;
+
+	if (queue->head != NULL) {
+		front = queue->head;
+		queue->head = queue->head->next;
+	}
+
+	return (front);
+}
+
+CK_CC_INLINE static bool
+ck_barrier_ct_queue_is_empty(struct ck_barrier_ct_queue *queue)
+{
+	return (queue->head == NULL);
+}
+
+CK_CC_INLINE static void
+ck_barrier_combining_init(struct ck_barrier_combining *root, 
+			  struct ck_barrier_combining_entry *init_root)
+{
+	init_root->k = 0;
+	init_root->count = 0;
+	init_root->sense = 0;
+	init_root->parent = init_root->lchild = init_root->rchild = NULL;
+
+	ck_spinlock_cas_init(&root->mutex);
+	root->root = init_root;
+
+	return;
+}
+
+CK_CC_INLINE static bool
+ck_barrier_combining_try_insert(struct ck_barrier_combining_entry *parent,
+				struct ck_barrier_combining_entry *tnode,
+				struct ck_barrier_combining_entry **child)
+{
+	if (*child == NULL) {
+		*child = tnode;
+		tnode->parent = parent;
+		parent->k++;
+
+		return (true);
+	}
+
+	return (false);
+}
+
+CK_CC_INLINE static void
+ck_barrier_combining_entry_init(struct ck_barrier_combining *root,
+				struct ck_barrier_combining_entry *tnode)
+{
+	struct ck_barrier_combining_entry *node;
+	struct ck_barrier_ct_queue queue;
+
+	ck_barrier_ct_queue_init(&queue);
+
+	tnode->k = 1;
+	tnode->count = 0;
+	tnode->sense = 0;
+	tnode->lchild = tnode->rchild = NULL;
+
+	ck_spinlock_cas_lock(&root->mutex);
+
+	ck_barrier_ct_queue_enqueue(&queue, root->root);
+	while (!ck_barrier_ct_queue_is_empty(&queue)) {
+		node = ck_barrier_ct_queue_dequeue(&queue);
+		if (ck_barrier_combining_try_insert(node, tnode, &node->lchild) == true) {
+			ck_spinlock_cas_unlock(&root->mutex);
+			return;
+		}
+		if (ck_barrier_combining_try_insert(node, tnode, &node->rchild) == true) {
+			ck_spinlock_cas_unlock(&root->mutex);
+			return;
+		}
+		ck_barrier_ct_queue_enqueue(&queue, node->lchild);
+		ck_barrier_ct_queue_enqueue(&queue, node->rchild);
+	}
+}
+
+CK_CC_INLINE static void
+ck_barrier_combining_aux(struct ck_barrier_combining *barrier,
+			 struct ck_barrier_combining_entry *tnode,
+			 unsigned int sense)
+{
+	/* Incrementing a leaf's count is unnecessary. */
+	if (tnode->lchild == NULL) {
+		ck_barrier_combining_aux(barrier, tnode->parent, sense);
+		ck_pr_store_uint(&tnode->sense, ~tnode->sense);
+		return;
+	}
+
+	if (ck_pr_faa_uint(&tnode->count, 1) == tnode->k - 1) {
+		if (tnode->parent != NULL)
+			ck_barrier_combining_aux(barrier, tnode->parent, sense);
+		ck_pr_store_uint(&tnode->count, 0);
+		ck_pr_store_uint(&tnode->sense, ~tnode->sense);
+	} else
+		while (sense != ck_pr_load_uint(&tnode->sense)) {
+			ck_pr_stall();
+		}
+
+	return;
+}
+
+CK_CC_INLINE static void
+ck_barrier_combining(struct ck_barrier_combining *barrier,
+		     struct ck_barrier_combining_entry *tnode,
+		     struct ck_barrier_combining_state *state)
+{
+	ck_barrier_combining_aux(barrier, tnode, state->sense);
+	state->sense = ~state->sense;
+}
+
+#endif /* CK_BARRIER_COMBINING */
+
 #endif /* _CK_BARRIER_H */
+
diff --git a/regressions/ck_barrier/validate/Makefile b/regressions/ck_barrier/validate/Makefile
index 28cc979..c6f54de 100644
--- a/regressions/ck_barrier/validate/Makefile
+++ b/regressions/ck_barrier/validate/Makefile
@@ -1,12 +1,15 @@
 .PHONY: clean distribution
 
-OBJECTS=validate 
+OBJECTS=validate combining_validate 
 
 all: $(OBJECTS)
 
 validate: validate.c ../../../include/ck_barrier.h
 	$(CC) $(CFLAGS) -o validate validate.c -lpthread
 
+combining_validate: combining_validate.c ../../../include/ck_barrier.h
+	$(CC) $(CFLAGS) -o combining_validate combining_validate.c -lpthread
+
 clean:
 	rm -rf *.dSYM *~ *.o $(OBJECTS)
 
diff --git a/regressions/ck_barrier/validate/combining_validate.c b/regressions/ck_barrier/validate/combining_validate.c
new file mode 100644
index 0000000..634f466
--- /dev/null
+++ b/regressions/ck_barrier/validate/combining_validate.c
@@ -0,0 +1,146 @@
+/*
+ * Copyright 2011 Samy Al Bahra.
+ * Copyright 2011 David Joseph.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <errno.h>
+#include <inttypes.h>
+#include <pthread.h>
+#include <math.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <strings.h>
+#include <unistd.h>
+#include <sys/time.h>
+
+#include <ck_pr.h>
+#include <ck_barrier.h>
+
+#include "../../common.h"
+
+#ifndef ITERATE
+#define ITERATE 5000000
+#endif
+
+#ifndef ENTRIES
+#define ENTRIES 512
+#endif
+
+static struct affinity a;
+static int nthr;
+static int counters[ENTRIES];
+static ck_barrier_combining_t barrier;
+static int barrier_wait;
+
+static void *
+thread(void *null CK_CC_UNUSED)
+{
+	ck_barrier_combining_entry_t *tnode;
+	ck_barrier_combining_state_t state = CK_BARRIER_COMBINING_STATE_INITIALIZER;
+	int j;
+	int i = 0;
+	int counter;
+
+	tnode = malloc(sizeof(ck_barrier_combining_entry_t));
+	if (tnode == NULL) {
+		fprintf(stderr, "Could not allocate thread barrier entry\n");
+		exit(EXIT_FAILURE);
+	}
+
+	ck_barrier_combining_entry_init(&barrier, tnode);
+
+	aff_iterate(&a);
+
+	ck_pr_inc_int(&barrier_wait);
+	while (ck_pr_load_int(&barrier_wait) != nthr)
+		ck_pr_stall();
+
+	for (j = 0; j < ITERATE; j++) {
+		i = j++ & (ENTRIES - 1);
+		ck_pr_inc_int(&counters[i]);
+		ck_barrier_combining(&barrier, tnode, &state);
+		counter = ck_pr_load_int(&counters[i]);
+		if (counter != nthr * (j / ENTRIES + 1)) {
+			fprintf(stderr, "FAILED [%d:%d]: %d != %d\n", i, j - 1, counter, nthr);
+			exit(EXIT_FAILURE);
+		}
+	}
+
+	free(tnode);
+	return (NULL);
+}
+
+int
+main(int argc, char *argv[])
+{
+	pthread_t *threads;
+	int i;
+	ck_barrier_combining_entry_t *init_root;
+
+	init_root = malloc(sizeof(ck_barrier_combining_entry_t));
+	if (init_root == NULL) {
+		fprintf(stderr, "ERROR: Could not allocate initial barrier structure\n");
+		exit(EXIT_FAILURE);
+	}	
+	ck_barrier_combining_init(&barrier, init_root);
+
+	if (argc != 3) {
+		fprintf(stderr, "Usage: correct <number of threads> <affinity delta>\n");
+		exit(EXIT_FAILURE);
+	}
+
+	nthr = atoi(argv[1]);
+	if (nthr <= 0) {
+		fprintf(stderr, "ERROR: Number of threads must be greater than 0\n");
+		exit(EXIT_FAILURE);
+	}
+
+	threads = malloc(sizeof(pthread_t) * nthr);
+	if (threads == NULL) {
+		fprintf(stderr, "ERROR: Could not allocate thread structures\n");
+		exit(EXIT_FAILURE);
+	}
+
+	a.delta = atoi(argv[2]);
+
+	fprintf(stderr, "Creating threads (barrier)...");
+	for (i = 0; i < nthr; i++) {
+		if (pthread_create(&threads[i], NULL, thread, NULL)) {
+			fprintf(stderr, "ERROR: Could not create thread %d\n", i);
+			exit(EXIT_FAILURE);
+		}
+	}
+	fprintf(stderr, "done\n");
+
+	fprintf(stderr, "Waiting for threads to finish correctness regression...");
+	for (i = 0; i < nthr; i++)
+		pthread_join(threads[i], NULL);
+	fprintf(stderr, "done (passed)\n");
+
+	free(init_root);
+	return (0);
+}
+