Instructional leaders require timely and predictive data to guide post-pandemic systemic changes. We investigated the predictability of an observational instrument, the Rigor Appraisal, and its association with achievement and other school effectiveness measures in a sample of 53 schools in Illinois. We found that increases in the Rigor Appraisal had a small to moderate and statistically significant association with achievement, a positive and moderate statistically significant association with attendance, a negative relationship between referrals and suspensions, and a positive and moderate statistically significant association with the 5Essentials. Additionally, the implementation of academic teaming was associated with greater achievement in schools with more low-income students. We also found that leaders who conducted non-evaluative instructional walks experienced a positive and statistically significant impact on achievement. As such, the Rigor Appraisal merits further study in different contexts, as it shows promise as a leading indicator that can be used for the continuous improvement of instructional systems.