Based on the 1993 California Learning Assessment System (CLAS) Middle Grades Mathematics Performance Assessment, an innovative alternative assessment, the study explores whether all schools, regardless of the cultural, ethnic, or socioeconomic background of the students they serve, provide students with equal opportunity to learn that which is assessed. Opportunity to learn was defined to include a range of variables likely to influence student performance, including access to resources, access to high-quality instructional content and processes, extra-school opportunities, and direct preparation for the CLAS. Data collection efforts included teacher interviews, student surveys, student retrospective think-aloud interviews, and classroom observations of the assessment administration. Researchers chose 13 schools across the state to represent three broad categories of schools: affluent suburban; low-socioeconomic-status (SES) urban; and remote, mixed SES rural schools. Findings highlight some differences between school types in various opportunity-to-learn measures and suggest directions for future research.