diff --git a/src/main/java/hudson/plugins/throttleconcurrents/ThrottleJobProperty.java b/src/main/java/hudson/plugins/throttleconcurrents/ThrottleJobProperty.java
index f2cba356..089e9790 100644
--- a/src/main/java/hudson/plugins/throttleconcurrents/ThrottleJobProperty.java
+++ b/src/main/java/hudson/plugins/throttleconcurrents/ThrottleJobProperty.java
@@ -17,6 +17,7 @@
 import hudson.matrix.MatrixProject;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
@@ -24,12 +25,14 @@
 import java.util.Map;
 import java.util.WeakHashMap;
 import java.util.concurrent.CopyOnWriteArrayList;
+
 import javax.annotation.CheckForNull;
 import javax.annotation.Nonnull;
-import jenkins.model.Jenkins;
 
+import jenkins.model.Jenkins;
 import net.sf.json.JSONObject;
 
+import org.apache.commons.lang.StringUtils;
 import org.kohsuke.stapler.DataBoundConstructor;
 import org.kohsuke.stapler.QueryParameter;
 import org.kohsuke.stapler.StaplerRequest;
@@ -322,6 +325,8 @@ public static final class ThrottleCategory extends AbstractDescribableImpl<Throt
         private Integer maxConcurrentPerNode;
         private Integer maxConcurrentTotal;
         private String categoryName;
+        private String blockingCategories;
+        private List<String> blockingCategoriesList = new ArrayList<String>();
         private List<NodeLabeledPair> nodeLabeledPairs;
 
         @DataBoundConstructor
@@ -335,7 +340,26 @@ public ThrottleCategory(String categoryName,
             this.nodeLabeledPairs =
                  nodeLabeledPairs == null ? new ArrayList<NodeLabeledPair>() : nodeLabeledPairs;
         }
+
+        @DataBoundConstructor
+        public ThrottleCategory(String categoryName,
+                                Integer maxConcurrentPerNode,
+                                Integer maxConcurrentTotal,
+                                String blockingCategories,
+                                List<NodeLabeledPair> nodeLabeledPairs) {
+            this(categoryName, maxConcurrentPerNode, maxConcurrentTotal, nodeLabeledPairs);
+            this.blockingCategories = blockingCategories;
+            convertCategoriesToList(blockingCategories);
+        }
         
+        private void convertCategoriesToList(String categoriesString) {
+            String[] catArray = StringUtils.split(categoriesString, ',');
+            catArray = StringUtils.stripAll(catArray);
+            if (catArray != null) {
+                Collections.addAll(blockingCategoriesList, catArray);
+            }
+        }
+
         public Integer getMaxConcurrentPerNode() {
             if (maxConcurrentPerNode == null)
                 maxConcurrentPerNode = 0;
@@ -354,6 +378,14 @@ public String getCategoryName() {
             return categoryName;
         }
 
+        public String getBlockingCategories() {
+            return blockingCategories;
+        }
+
+        public List<String> getBlockingCategoriesList() {
+            return blockingCategoriesList;
+        }
+
         public List<NodeLabeledPair> getNodeLabeledPairs() {
             if (nodeLabeledPairs == null)
                 nodeLabeledPairs = new ArrayList<NodeLabeledPair>();
diff --git a/src/main/java/hudson/plugins/throttleconcurrents/ThrottleQueueTaskDispatcher.java b/src/main/java/hudson/plugins/throttleconcurrents/ThrottleQueueTaskDispatcher.java
index eb1abece..8eb79b71 100644
--- a/src/main/java/hudson/plugins/throttleconcurrents/ThrottleQueueTaskDispatcher.java
+++ b/src/main/java/hudson/plugins/throttleconcurrents/ThrottleQueueTaskDispatcher.java
@@ -1,5 +1,6 @@
 package hudson.plugins.throttleconcurrents;
 
+
 import hudson.Extension;
 import hudson.matrix.MatrixConfiguration;
 import hudson.matrix.MatrixProject;
@@ -13,14 +14,18 @@
 import hudson.model.labels.LabelAtom;
 import hudson.model.queue.CauseOfBlockage;
 import hudson.model.queue.QueueTaskDispatcher;
+import hudson.plugins.throttleconcurrents.ThrottleJobProperty.ThrottleCategory;
 
 import java.util.List;
 import java.util.Set;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+
 import javax.annotation.CheckForNull;
 import javax.annotation.Nonnull;
 
+import org.apache.commons.lang.StringUtils;
+
 @Extension
 public class ThrottleQueueTaskDispatcher extends QueueTaskDispatcher {
 
@@ -153,6 +158,11 @@ else if (tjp.getThrottleOption().equals("category")) {
 
                         // Double check category itself isn't null
                         if (category != null) {
+                            // Check if this job is blocked by category
+                            if (isBlockedByCategories(category.getBlockingCategoriesList())) {
+                                return CauseOfBlockage.fromMessage(Messages._ThrottleQueueTaskDispatcher_BlockedByCategory());
+                            }
+
                             if (category.getMaxConcurrentTotal().intValue() > 0) {
                                 int maxConcurrentTotal = category.getMaxConcurrentTotal().intValue();
                                 int totalRunCount = 0;
@@ -178,6 +188,32 @@ else if (tjp.getThrottleOption().equals("category")) {
         return null;
     }
 
+    private boolean isBlockedByCategories(List<String> categoryNames) {
+        for (String catName : categoryNames) {
+            if (areProjectsInCategoryBuilding(catName)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private boolean areProjectsInCategoryBuilding(String categoryName) {
+        List<AbstractProject<?, ?>> projectsInCategory = ThrottleJobProperty.getCategoryProjects(categoryName);
+        for (AbstractProject<?, ?> project : projectsInCategory) {
+            if (isProjectBuilding(project)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private boolean isProjectBuilding(AbstractProject<?, ?> project) {
+        if (project.isBuilding() || project.isInQueue()) {
+            return true;
+        }
+        return false;
+    }
+
     @CheckForNull
     private ThrottleJobProperty getThrottleJobProperty(Task task) {
         if (task instanceof AbstractProject) {
diff --git a/src/main/resources/hudson/plugins/throttleconcurrents/Messages.properties b/src/main/resources/hudson/plugins/throttleconcurrents/Messages.properties
index 949b92e3..0bb18f51 100644
--- a/src/main/resources/hudson/plugins/throttleconcurrents/Messages.properties
+++ b/src/main/resources/hudson/plugins/throttleconcurrents/Messages.properties
@@ -1,5 +1,6 @@
 ThrottleQueueTaskDispatcher.MaxCapacityOnNode=Already running {0} builds on node
 ThrottleQueueTaskDispatcher.MaxCapacityTotal=Already running {0} builds across all nodes
 ThrottleQueueTaskDispatcher.BuildPending=A build is pending launch
+ThrottleQueueTaskDispatcher.BlockedByCategory=Build is blocked by jobs in another category
 
 ThrottleMatrixProjectOptions.DisplayName=Additional options for Matrix projects
\ No newline at end of file
diff --git a/src/main/resources/hudson/plugins/throttleconcurrents/ThrottleJobProperty/global.jelly b/src/main/resources/hudson/plugins/throttleconcurrents/ThrottleJobProperty/global.jelly
index 1a6db694..8f2b4efc 100644
--- a/src/main/resources/hudson/plugins/throttleconcurrents/ThrottleJobProperty/global.jelly
+++ b/src/main/resources/hudson/plugins/throttleconcurrents/ThrottleJobProperty/global.jelly
@@ -13,6 +13,9 @@
           <f:entry title="${%Maximum Concurrent Builds Per Node}" field="maxConcurrentPerNode">
             <f:textbox />
           </f:entry>
+          <f:entry title="${%Blocking Categories}" field="blockingCategories">
+            <f:textbox />
+          </f:entry>
         </table>
         <f:repeatable field="nodeLabeledPairs" add="${%Add Maximum Per Labeled Node}" minimum="0" header="${%Maximum Per Labeled Node}">
           <table width="100%">
diff --git a/src/test/java/hudson/plugins/throttleconcurrents/ThrottleCategoryTest.java b/src/test/java/hudson/plugins/throttleconcurrents/ThrottleCategoryTest.java
index d0488566..68c40731 100644
--- a/src/test/java/hudson/plugins/throttleconcurrents/ThrottleCategoryTest.java
+++ b/src/test/java/hudson/plugins/throttleconcurrents/ThrottleCategoryTest.java
@@ -36,7 +36,7 @@ public class ThrottleCategoryTest
     public void shouldGetEmptyNodeLabeledPairsListUponInitialNull()
     {
         ThrottleJobProperty.ThrottleCategory category =
-            new ThrottleJobProperty.ThrottleCategory(testCategoryName, 0, 0, null);
+            new ThrottleJobProperty.ThrottleCategory(testCategoryName, 0, 0, null, null);
         assertTrue("nodeLabeledPairs shall be empty", category.getNodeLabeledPairs().isEmpty());
     }
 
@@ -47,7 +47,7 @@ public void shouldGetNonEmptyNodeLabeledPairsListThatWasSet()
         Integer expectedMax = new Integer(1);
 
         ThrottleJobProperty.ThrottleCategory category =
-            new ThrottleJobProperty.ThrottleCategory(testCategoryName, 0, 0, null);
+            new ThrottleJobProperty.ThrottleCategory(testCategoryName, 0, 0, "", null);
         List<ThrottleJobProperty.NodeLabeledPair> nodeLabeledPairs = category.getNodeLabeledPairs();
         nodeLabeledPairs.add(new ThrottleJobProperty.NodeLabeledPair(expectedLabel, expectedMax));