Index: lams_gradebook/src/java/org/lamsfoundation/lams/gradebook/service/GradebookService.java
===================================================================
diff -u -rdabbd69e717a9fa6ea189cd88e66540772bae9fe -rda1be8146d2ef06173298f684230e39a691d707a
--- lams_gradebook/src/java/org/lamsfoundation/lams/gradebook/service/GradebookService.java	(.../GradebookService.java)	(revision dabbd69e717a9fa6ea189cd88e66540772bae9fe)
+++ lams_gradebook/src/java/org/lamsfoundation/lams/gradebook/service/GradebookService.java	(.../GradebookService.java)	(revision da1be8146d2ef06173298f684230e39a691d707a)
@@ -25,6 +25,7 @@
 
 import java.text.DateFormat;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Date;
 import java.util.HashMap;
@@ -53,6 +54,7 @@
 import org.lamsfoundation.lams.gradebook.util.GBGridView;
 import org.lamsfoundation.lams.gradebook.util.GradebookConstants;
 import org.lamsfoundation.lams.gradebook.util.LessonComparator;
+import org.lamsfoundation.lams.gradebook.util.UserComparator;
 import org.lamsfoundation.lams.learningdesign.Activity;
 import org.lamsfoundation.lams.learningdesign.Group;
 import org.lamsfoundation.lams.learningdesign.Grouping;
@@ -610,10 +612,11 @@
 
 	HashMap<ToolActivity, List<GBUserGridRowDTO>> activityToUserDTOMap = new HashMap<ToolActivity, List<GBUserGridRowDTO>>();
 
-	Set<User> learners = lesson.getAllLearners();
-	if (learners == null) {
-	    learners = new TreeSet<User>();
+	Set<User> learners = new TreeSet<User>(new UserComparator());
+	if (lesson.getAllLearners() != null) {
+	    learners.addAll(lesson.getAllLearners());
 	}
+	
 	Map<Integer, LearnerProgress> userToLearnerProgressMap = getUserToLearnerProgressMap(lesson, null);
 	Set<ToolActivity> activities = getLessonActivities(lesson);
 
@@ -764,9 +767,9 @@
 
 	// -------------------- process Learner View page --------------------------------
 
-	Set<User> learners = lesson.getAllLearners();
-	if (learners == null) {
-	    learners = new TreeSet<User>();
+	Set<User> learners = new TreeSet<User>(new UserComparator());
+	if (lesson.getAllLearners() != null) {
+	    learners.addAll(lesson.getAllLearners());
 	}
 
 	rowList = new LinkedList<ExcelCell[]>();
@@ -869,7 +872,7 @@
 	    rowList.add(headerRow);
 
 	    // collect users from all lessons
-	    Set<User> allLearners = new LinkedHashSet<User>();
+	    LinkedHashSet<User> allLearners = new LinkedHashSet<User>();
 	    List<Long> lessonIds = new LinkedList<Long>();
 	    for (Lesson lesson : lessons) {
 		Set dbLessonUsers = lesson.getAllLearners();
@@ -880,16 +883,20 @@
 	    // Fetching the user data
 	    List<LearnerProgress> learnerProgresses;
 	    List<GradebookUserLesson> gradebookUserLessons;
-	    if (allLearners == null || allLearners.isEmpty()) {
+	    if (allLearners.isEmpty()) {
 		learnerProgresses = new LinkedList<LearnerProgress>();
 		gradebookUserLessons = new LinkedList<GradebookUserLesson>();
 		
 	    } else {
 		learnerProgresses = learnerProgressDAO.getLearnerProgressForLessons(lessonIds);
 		gradebookUserLessons = gradebookDAO.getGradebookUserLessons(lessonIds);
 	    }
+	    
+	    //sort users by last name
+	    TreeSet<User> sortedLearners = new TreeSet<User>(new UserComparator());
+	    sortedLearners.addAll(allLearners);
 
-	    for (User learner : allLearners) {
+	    for (User learner : sortedLearners) {
 		i = 0;
 		ExcelCell[] userDataRow = new ExcelCell[numberOfCellsInARow];
 		userDataRow[i++] = new ExcelCell(learner.getLastName(), false);
Index: lams_gradebook/src/java/org/lamsfoundation/lams/gradebook/util/UserComparator.java
===================================================================
diff -u
--- lams_gradebook/src/java/org/lamsfoundation/lams/gradebook/util/UserComparator.java	(revision 0)
+++ lams_gradebook/src/java/org/lamsfoundation/lams/gradebook/util/UserComparator.java	(revision da1be8146d2ef06173298f684230e39a691d707a)
@@ -0,0 +1,16 @@
+package org.lamsfoundation.lams.gradebook.util;
+
+import java.util.Comparator;
+
+import org.apache.commons.lang.builder.CompareToBuilder;
+import org.lamsfoundation.lams.usermanagement.User;
+
+/**
+ * Sorts users by last names.
+ */
+public class UserComparator implements Comparator<User> {
+    public int compare(User o1, User o2) {
+	return new CompareToBuilder().append(o1.getLastName(), o2.getLastName())
+		.append(o1.getFirstName(), o2.getFirstName()).append(o1.getLogin(), o2.getLogin()).toComparison();
+    }
+}