Large-scale educational assessment has gone through many changes in recent decades, but none has implications for the practice of measurement so great as the shift to using tests as a means of holding educators and educational systems accountable. Achievement testing has never been entirely free of this purpose, but the balance of goals has shifted greatly, and accountability has become the most important function of many large-scale testing programs in the United States (Koretz & Hamilton, 2006) and increasingly in other nations as well.