This paper contrasts the positions of Kane and Staiger (2002) and Linn and Haug (2002) with that of Rogosa (2002, 2003a) on the volatility in test scores as measures of school growth. In particular, these researchers disagree on whether school growth can be measured reliably in school accountability systems. The different positions of these authors are examined in some detail. In addition, several issues related to their debate are examined in the context of the No Child Left Behind (NCLB) legislation, which has imposed a particular structure on the accountability systems currently in place in many states. Finally, some possibilities and speculations about the future of school accountability systems are provided in relation to the NCLB requirements and their impact.