Index: modeshape-jcr/src/main/java/org/modeshape/jcr/JcrLexicon.java
===================================================================
--- modeshape-jcr/src/main/java/org/modeshape/jcr/JcrLexicon.java	(revision 1908)
+++ modeshape-jcr/src/main/java/org/modeshape/jcr/JcrLexicon.java	(working copy)
@@ -39,6 +39,7 @@ public class JcrLexicon extends org.modeshape.graph.JcrLexicon {
     public static final Name COPIED_FROM = new BasicName(Namespace.URI, "copiedFrom");
     public static final Name DATA = new BasicName(Namespace.URI, "data");
     public static final Name ENCODING = new BasicName(Namespace.URI, "encoding");
+    public static final Name ETAG = new BasicName(Namespace.URI, "etag");
     public static final Name FROZEN_MIXIN_TYPES = new BasicName(Namespace.URI, "frozenMixinTypes");
     public static final Name FROZEN_NODE = new BasicName(Namespace.URI, "frozenNode");
     public static final Name FROZEN_PRIMARY_TYPE = new BasicName(Namespace.URI, "frozenPrimaryType");
Index: modeshape-jcr/src/main/java/org/modeshape/jcr/JcrMixLexicon.java
===================================================================
--- modeshape-jcr/src/main/java/org/modeshape/jcr/JcrMixLexicon.java	(revision 1908)
+++ modeshape-jcr/src/main/java/org/modeshape/jcr/JcrMixLexicon.java	(working copy)
@@ -24,6 +24,8 @@
 package org.modeshape.jcr;
 
 import net.jcip.annotations.Immutable;
+import org.modeshape.graph.property.Name;
+import org.modeshape.graph.property.basic.BasicName;
 
 /**
  * Lexicon of names from the standard JCR "<code>http://www.jcp.org/jcr/mix/1.0</code>" namespace.
@@ -31,4 +33,6 @@ import net.jcip.annotations.Immutable;
 @Immutable
 public class JcrMixLexicon extends org.modeshape.graph.JcrMixLexicon {
 
+    public static final Name ETAG = new BasicName(Namespace.URI, "etag");
+
 }
Index: modeshape-jcr/src/main/java/org/modeshape/jcr/SessionCache.java
===================================================================
--- modeshape-jcr/src/main/java/org/modeshape/jcr/SessionCache.java	(revision 1908)
+++ modeshape-jcr/src/main/java/org/modeshape/jcr/SessionCache.java	(working copy)
@@ -60,6 +60,8 @@ import org.modeshape.graph.ExecutionContext;
 import org.modeshape.graph.Graph;
 import org.modeshape.graph.Location;
 import org.modeshape.graph.connector.RepositorySourceException;
+import org.modeshape.graph.property.Binary;
+import org.modeshape.graph.property.BinaryFactory;
 import org.modeshape.graph.property.DateTime;
 import org.modeshape.graph.property.Name;
 import org.modeshape.graph.property.NameFactory;
@@ -2644,6 +2646,7 @@ class SessionCache {
             JcrNodeType primaryType = nodeTypes().getNodeType(primaryTypeName);
             boolean isLastModifiedType = primaryType.isNodeType(JcrMixLexicon.LAST_MODIFIED);
             boolean isCreatedType = primaryType.isNodeType(JcrMixLexicon.CREATED);
+            boolean isETag = primaryType.isNodeType(JcrMixLexicon.ETAG);
             for (JcrPropertyDefinition definition : primaryType.getPropertyDefinitions()) {
                 if (definition.isMandatory() && !definition.isProtected() && !satisfiedProperties.contains(definition)) {
                     throw new ValidationException(JcrI18n.noDefinition.text("property",
@@ -2668,6 +2671,7 @@ class SessionCache {
                     JcrNodeType mixinType = nodeTypes().getNodeType(mixinTypeName);
                     isLastModifiedType = isLastModifiedType || mixinType.isNodeType(JcrMixLexicon.LAST_MODIFIED);
                     isCreatedType = isCreatedType || mixinType.isNodeType(JcrMixLexicon.CREATED);
+                    isETag = isETag || mixinType.isNodeType(JcrMixLexicon.ETAG);
                     for (JcrPropertyDefinition definition : mixinType.getPropertyDefinitions()) {
                         if (definition.isMandatory() && !definition.isProtected() && !satisfiedProperties.contains(definition)) {
                             throw new ValidationException(JcrI18n.noDefinition.text("child node",
@@ -2690,6 +2694,43 @@ class SessionCache {
                 }
             }
 
+            // Do we need to update the 'jcr:etag' property?
+            if (isETag) {
+                // Per section 3.7.12 of JCR 2, this property should be changed whenever BINARY properties are added, removed, or
+                // changed. So, go through the properties (in sorted-name order so it is repeatable) and create this value
+                // by simply concatenating the SHA-1 hash of each BINARY value ...
+                List<Name> binaryPropertyNames = new ArrayList<Name>();
+                for (org.modeshape.graph.session.GraphSession.PropertyInfo<JcrPropertyPayload> property : node.getProperties()) {
+                    if (property.getProperty().size() == 0) continue;
+                    if (property.getPayload().getPropertyType() != PropertyType.BINARY) continue;
+                    binaryPropertyNames.add(property.getName());
+                }
+                if (!binaryPropertyNames.isEmpty()) {
+                    Collections.sort(binaryPropertyNames);
+                    BinaryFactory binaryFactory = context().getValueFactories().getBinaryFactory();
+                    StringBuilder sb = new StringBuilder();
+                    for (Name name : binaryPropertyNames) {
+                        org.modeshape.graph.session.GraphSession.PropertyInfo<JcrPropertyPayload> property = node.getProperty(name);
+                        for (Object value : property.getProperty()) {
+                            Binary binary = binaryFactory.create(value);
+                            String hash = new String(binary.getHash()); // doesn't matter what charset, as long as its always the
+                            // same
+                            sb.append(hash);
+                        }
+                    }
+                    if (sb.length() != 0) {
+                        String etagValue = sb.toString();
+                        setPropertyIfAbsent(node,
+                                            primaryTypeName,
+                                            mixinTypeNames,
+                                            false,
+                                            JcrLexicon.ETAG,
+                                            PropertyType.STRING,
+                                            etagValue);
+                    }
+                }
+            }
+
             // See if the node is an instance of 'mix:created'.
             // This is done even if the node is not newly-created, because this needs to happen whenever the
             // 'mix:created' node type is added as a mixin (which can happen to an existing node).
Index: modeshape-jcr/src/main/resources/org/modeshape/jcr/jsr_283_builtins.cnd
===================================================================
--- modeshape-jcr/src/main/resources/org/modeshape/jcr/jsr_283_builtins.cnd	(revision 1908)
+++ modeshape-jcr/src/main/resources/org/modeshape/jcr/jsr_283_builtins.cnd	(working copy)
@@ -163,6 +163,9 @@
 //                             Pre-defined Mixins
 // ------------------------------------------------------------------------
 
+[mix:etag] mixin
+  - jcr:etag (string) protected autocreated
+
 [mix:lockable] mixin 
   - jcr:lockOwner (string) protected ignore 
   - jcr:lockIsDeep (boolean) protected ignore