Value added measures (VAM) uses changes in student test scores to determine how much "value" an individual teacher has "added" to student growth during the school year. Some policymakers, school districts, and educational advocates have applauded VAM as a straightforward measure of teacher effectiveness: the better a teacher, the better students will perform on standardized tests. However, many prominent researchers and educators have expressed concern and urged caution. This paper presents a series of questions and answers (as well as resources for more indepth analysis) aimed at disentangling this complex issue. In particular, it is concerned that a narrow use of "value added" as the single measure of teacher effectiveness will have a detrimental effect on student learning, teacher retention, and educational equity. In other words, without more careful implementation and use, VAM could exacerbate the very problems they are alleged to help address. (Contains 28 endnotes.)