This study investigated the sustainability effects of the schema-based instruction (SBI) program and corresponding PD on the instructional practices of two cohorts of teachers (i.e., SBI experienced-teacher implementers and SBI novice-teacher implementers) and on students' ability to reason with proportions and overall mathematics performance. SBI is a multicomponent program that focuses on recognizing the underlying mathematical problem structure (e.g., ratios, rates, percent) needed to reason with proportions. Results indicated that both experienced- and novice-teacher implementers delivered SBI with similar levels of fidelity; there was an SBI experience effect on the immediate test of proportional problem-solving (PPS), but not on a 11-week retention test of PPS, a general measure of problem solving, or the end-of-year state mathematics achievement tests.