School media specialists collaborate with many teachers every day. They are so good that sometimes they even collaborate without realizing it. Sometimes, however, a more formal type of collaboration is needed. Not only does formal collaboration give them a chance to shine as the instructional leader, it also allows them to collect data to show that what they are doing (even in informal cases) makes a difference in terms of student achievement. In this data-driven educational world, this type of data is invaluable for School Improvement, NCLB, and other state accountability measures. Much work has been done recently on collaboration--how to collaborate, collaboration ideas, collaboration tools--extremely beneficial and helpful to school library media specialists. This article, however, deals with taking the next step and determining the success of these collaboration efforts. By using data to assess collaboration units, library media specialists can see the progress they are making as they climb the ladder and, just as importantly, show that progress to others.