Conclusions & Implications: The strongest correlate of true teaching effectiveness was the estimate of teacher contribution to student achievement on the same test a year later. However, this correlation was only modest (.30). All other measures including effectiveness measures based on alternative tests and student, parent and administrator perceptions of teacher effectiveness were less correlated with the original value-added estimate, thus raising questions about the usefulness of any of these other measures. Because the value-added measure turns out to be the best predictor of itself in a subsequent year, this estimate alone trumps all others in terms of usefulness for making decisions regarding teacher retention (especially in times of staffing reduction) and should also be considered a primary factor in compensation decisions. Note that while it may appear that school administrators, students and their parents have highly consistent views regarding which teachers are more and less effective (note the higher correlations across administrator ratings of teachers, and student and parent ratings), we consider these findings unimportant because none of these perception-based ratings were as correlated with the original value-added estimate as the value-added estimate was with itself (which of course, is the TRUE measure of effectiveness).