Index: src/test/com/thoughtworks/acceptance/FieldAliasTest.java
===================================================================
--- src/test/com/thoughtworks/acceptance/FieldAliasTest.java	(revision 0)
+++ src/test/com/thoughtworks/acceptance/FieldAliasTest.java	(revision 0)
@@ -0,0 +1,81 @@
+package com.thoughtworks.acceptance;
+
+import com.thoughtworks.acceptance.objects.Software;
+import com.thoughtworks.acceptance.objects.OpenSourceSoftware;
+
+import java.util.ArrayList;
+
+/**
+ * @author David Blevins
+ */
+public class FieldAliasTest extends AbstractAcceptanceTest {
+
+    public void testAllowsIndividualFieldsToBeAliased() {
+        Software in = new Software("ms", "word");
+        xstream.alias("software", Software.class);
+        xstream.aliasField("CUSTOM-VENDOR", Software.class, "vendor");
+        xstream.aliasField("CUSTOM-NAME", Software.class, "name");
+
+        String expectedXml = "" +
+                "<software>\n" +
+                "  <CUSTOM-VENDOR>ms</CUSTOM-VENDOR>\n" +
+                "  <CUSTOM-NAME>word</CUSTOM-NAME>\n" +
+                "</software>";
+
+        assertBothWays(in, expectedXml);
+    }
+
+
+    public void testInheritsFieldAliasFromSuperclass() {
+        ArrayList software = new ArrayList();
+        software.add(new Software("ms", "word"));
+        software.add(new OpenSourceSoftware("apache", "geronimo", "asl 2.0"));
+
+        xstream.alias("oss", OpenSourceSoftware.class);
+        xstream.alias("software", Software.class);
+        xstream.aliasField("CUSTOM-VENDOR", Software.class, "vendor");
+        xstream.aliasField("CUSTOM-NAME", Software.class, "name");
+
+        String expectedXml = "" +
+                "<list>\n" +
+                "  <software>\n" +
+                "    <CUSTOM-VENDOR>ms</CUSTOM-VENDOR>\n" +
+                "    <CUSTOM-NAME>word</CUSTOM-NAME>\n" +
+                "  </software>\n" +
+                "  <oss>\n" +
+                "    <license>asl 2.0</license>\n" +
+                "    <CUSTOM-VENDOR>apache</CUSTOM-VENDOR>\n" +
+                "    <CUSTOM-NAME>geronimo</CUSTOM-NAME>\n" +
+                "  </oss>\n" +
+                "</list>";
+
+        assertBothWays(software, expectedXml);
+    }
+
+    public void testAllowsSubclassToOverrideFieldAliasInSuperclass() {
+        ArrayList software = new ArrayList();
+        software.add(new Software("ms", "word"));
+        software.add(new OpenSourceSoftware("apache", "geronimo", "asl 2.0"));
+
+        xstream.alias("oss", OpenSourceSoftware.class);
+        xstream.aliasField("ORGANIZATION", OpenSourceSoftware.class, "vendor");
+        xstream.alias("software", Software.class);
+        xstream.aliasField("CUSTOM-VENDOR", Software.class, "vendor");
+        xstream.aliasField("CUSTOM-NAME", Software.class, "name");
+
+        String expectedXml = "" +
+                "<list>\n" +
+                "  <software>\n" +
+                "    <CUSTOM-VENDOR>ms</CUSTOM-VENDOR>\n" +
+                "    <CUSTOM-NAME>word</CUSTOM-NAME>\n" +
+                "  </software>\n" +
+                "  <oss>\n" +
+                "    <license>asl 2.0</license>\n" +
+                "    <ORGANIZATION>apache</ORGANIZATION>\n" +
+                "    <CUSTOM-NAME>geronimo</CUSTOM-NAME>\n" +
+                "  </oss>\n" +
+                "</list>";
+
+        assertBothWays(software, expectedXml);
+    }
+}
Index: src/java/com/thoughtworks/xstream/mapper/FieldAliasingMapper.java
===================================================================
--- src/java/com/thoughtworks/xstream/mapper/FieldAliasingMapper.java	(revision 847)
+++ src/java/com/thoughtworks/xstream/mapper/FieldAliasingMapper.java	(working copy)
@@ -12,6 +12,7 @@
  * entirely.
  *
  * @author Joe Walnes
+ * @author David Blevins
  */
 public class FieldAliasingMapper extends MapperWrapper {
 
@@ -35,12 +36,12 @@
         aliasToFieldMap.put(key(type, alias), fieldName);
     }
 
-    private Object key(Class type, String value) {
-        return type.getName() + '.' + value;
+    private Key key(Class type, String value) {
+        return new Key(type, value);
     }
 
     public String serializedMember(Class type, String memberName) {
-        String alias = (String) fieldToAliasMap.get(key(type, memberName));
+        String alias = get(key(type, memberName), fieldToAliasMap);
         if (alias == null) {
             return super.serializedMember(type, memberName);
         } else {
@@ -49,7 +50,7 @@
     }
 
     public String realMember(Class type, String serialized) {
-        String real = (String) aliasToFieldMap.get(key(type, serialized));
+        String real = get(key(type, serialized), aliasToFieldMap);
         if (real == null) {
             return super.realMember(type, serialized);
         } else {
@@ -64,4 +65,66 @@
     public void omitField(Class type, String fieldName) {
         fieldsToOmit.add(key(type, fieldName));
     }
+
+    private String get(Key key, Map map){
+        String value = (String) map.get(key);
+        if (value != null){
+            return value;
+        }
+
+        Class superclass = key.getType().getSuperclass();
+
+        if (superclass == null || superclass == Object.class){
+            return null;
+        }
+
+        value = get(new Key(superclass, key.getName()), map);
+
+        if (value != null){
+            map.put(key, value);
+        }
+
+        return value;
+    }
+
+    private static class Key {
+        private final Class type;
+        private final String name;
+
+        public Key(Class type, String name) {
+            this.type = type;
+            this.name = name;
+        }
+
+        public Class getType() {
+            return type;
+        }
+
+        public String getName() {
+            return name;
+        }
+
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+
+            final Key key = (Key) o;
+
+            if (name != null ? !name.equals(key.name) : key.name != null) return false;
+            if (type != null ? !type.equals(key.type) : key.type != null) return false;
+
+            return true;
+        }
+
+        public int hashCode() {
+            int result;
+            result = (type != null ? type.hashCode() : 0);
+            result = 29 * result + (name != null ? name.hashCode() : 0);
+            return result;
+        }
+
+        public String toString() {
+            return "key("+type.getName()+", "+name+")";
+        }
+    }
 }
Index: src/java/com/thoughtworks/xstream/converters/reflection/AbstractReflectionConverter.java
===================================================================
--- src/java/com/thoughtworks/xstream/converters/reflection/AbstractReflectionConverter.java	(revision 847)
+++ src/java/com/thoughtworks/xstream/converters/reflection/AbstractReflectionConverter.java	(working copy)
@@ -71,13 +71,13 @@
                             Collection list = (Collection) newObj;
                             for (Iterator iter = list.iterator(); iter.hasNext();) {
                                 Object obj = iter.next();
-                                writeField(fieldName, mapping.getItemFieldName(), mapping.getItemType(), definedIn, obj);
+                                writeField(fieldName, mapping.getItemFieldName(), mapping.getItemType(), source.getClass(), obj);
                             }
                         } else {
                             context.convertAnother(newObj);
                         }
                     } else {
-                        writeField(fieldName, fieldName, fieldType, definedIn, newObj);
+                        writeField(fieldName, fieldName, fieldType, source.getClass(), newObj);
                         seenFields.add(fieldName);
                     }
                 }