Principal instructional leadership has been found to support improved instruction. However, the methods through which principal leadership influences classroom instruction are less clear. This study investigates how principals' leadership may predict the expectations that mathematics teachers perceive for classroom practice. Results from a hierarchical generalized linear (HGLM) model, using data from four urban school districts, show that the principal's work to frame instructional vision, and the principal's own vision, both predict perceived instructional expectations. However, other conventional leadership activities are not predictive. Finally, principals appear to provide a baseline of expectations for standards-based mathematics instruction rather than comprehensive expectations.