The use of "value added" information appears poised to expand into the nation's teacher colleges, with more than a dozen states planning to use the technique to analyze how graduates of training programs fare in classrooms. Supporters say the data could help determine which teacher education pathways produce teachers who are at least as good as--or even better than--other novice teachers, spurring weaker providers to emulate those colleges' practices. The two states with the most experience using such data, Louisiana and Tennessee, have shown that it can be a powerful catalyst for change. Both can point to programs that have seen improvements in value-added scores after altering aspects of their programming. Nevertheless, teacher-educators and state officials alike continue to wrestle with how best to translate what are, in essence, fairly blunt measures of program effectiveness into a regular cycle for improving teacher education curricula. For a concept that is only about a decade old, value-added is poised to expand rapidly in teacher education. The basic idea behind value-added is to examine growth in student test scores, holding constant factors like poverty or family characteristics that could skew scores, and then to determine what impact teachers had on that improvement. For teacher education, the process goes a step further, by analyzing how graduates of particular programs have done in the aggregate to raise their students' scores.