Ability grouping and tracking have been a major focus in educational research because of its role in promoting curriculum differentiation. However, there has been limited attention to how this differentiation occurs in contemporary schools involved with reform efforts including those focused on subject specific academic standards designed to improve student access to rigorous academic content. This article examines how varying teacher expectations regarding the implementation of academic standards promotes curriculum differentiation in middle schools involved with comprehensive school reform. Drawing on teacher interview and survey data from five middle schools, the author shows the challenges teachers confronted when implementing standards; the contradictory expectations teachers held toward students; and how teacher expectations affected to what extent standards were evenly applied. Despite the fact that standards are supposed to promote equity, this analysis shows these aims can be compromised by the challenges teachers confront in schools and contradictory expectations regarding standards.