diff --git a/CHANGES.txt b/CHANGES.txt
index c0e132d09a5..ad8a47c3fe9 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -65,6 +65,10 @@ Optimizations
 
  4. LUCENE-959: Remove synchronization in Document (yonik)
 
+ 5. LUCENE-963: Add setters to Field to allow for re-using a single
+    Field instance during indexing.  This is a sizable performance
+    gain, especially for small documents.  (Mike McCandless)
+
 Documentation
 
 Build
diff --git a/src/java/org/apache/lucene/document/Field.java b/src/java/org/apache/lucene/document/Field.java
index 5a1b4c3e581..16d932633ab 100644
--- a/src/java/org/apache/lucene/document/Field.java
+++ b/src/java/org/apache/lucene/document/Field.java
@@ -155,6 +155,35 @@ public final class Field extends AbstractField implements Fieldable, Serializabl
    * readerValue(), binaryValue(), and tokenStreamValue() must be set. */
   public TokenStream tokenStreamValue()   { return fieldsData instanceof TokenStream ? (TokenStream)fieldsData : null; }
   
+
+  /** Expert: change the value of this field.  This can be
+   *  used during indexing to re-use a single Field instance
+   *  to improve indexing speed. */
+  public void setValue(String value) {
+    fieldsData = value;
+  }
+
+  /** Expert: change the value of this field.  This can be
+   *  used during indexing to re-use a single Field instance
+   *  to improve indexing speed. */
+  public void setValue(Reader value) {
+    fieldsData = value;
+  }
+
+  /** Expert: change the value of this field.  This can be
+   *  used during indexing to re-use a single Field instance
+   *  to improve indexing speed. */
+  public void setValue(byte[] value) {
+    fieldsData = value;
+  }
+
+  /** Expert: change the value of this field.  This can be
+   *  used during indexing to re-use a single Field instance
+   *  to improve indexing speed. */
+  public void setValue(TokenStream value) {
+    fieldsData = value;
+  }
+
   /**
    * Create a field by specifying its name, value and how it will
    * be saved in the index. Term vectors will not be stored in the index.
diff --git a/src/test/org/apache/lucene/document/TestDocument.java b/src/test/org/apache/lucene/document/TestDocument.java
index 6b8b77bf66d..a28b1da28ef 100644
--- a/src/test/org/apache/lucene/document/TestDocument.java
+++ b/src/test/org/apache/lucene/document/TestDocument.java
@@ -222,4 +222,45 @@ public class TestDocument extends TestCase
             assertTrue(unstoredFieldValues[1].equals("test2"));
         }
     }
+
+    public void testFieldSetValue() throws Exception {
+
+      Field field = new Field("id", "id1", Field.Store.YES, Field.Index.UN_TOKENIZED);
+      Document doc = new Document();
+      doc.add(field);
+      doc.add(new Field("keyword", "test", Field.Store.YES, Field.Index.UN_TOKENIZED));
+
+      RAMDirectory dir = new RAMDirectory();
+      IndexWriter writer = new IndexWriter(dir, new StandardAnalyzer(), true);
+      writer.addDocument(doc);
+      field.setValue("id2");
+      writer.addDocument(doc);
+      field.setValue("id3");
+      writer.addDocument(doc);
+      writer.close();
+
+      Searcher searcher = new IndexSearcher(dir);
+
+      Query query = new TermQuery(new Term("keyword", "test"));
+
+      // ensure that queries return expected results without DateFilter first
+      Hits hits = searcher.search(query);
+      assertEquals(3, hits.length());
+      int result = 0;
+      for(int i=0;i<3;i++) {
+        Document doc2 = hits.doc(i);
+        Field f = doc2.getField("id");
+        if (f.stringValue().equals("id1"))
+          result |= 1;
+        else if (f.stringValue().equals("id2"))
+          result |= 2;
+        else if (f.stringValue().equals("id3"))
+          result |= 4;
+        else
+          fail("unexpected id field");
+      }
+      searcher.close();
+      dir.close();
+      assertEquals("did not see all IDs", 7, result);
+    }
 }