Class-size reduction (CSR) mandates presuppose that resources provided to reduce class size will have a larger impact on student outcomes than resources that districts can spend as they see fit. I estimate the impact of Florida's statewide CSR policy by comparing the deviations from prior achievement trends in districts that were required to reduce class size to deviations from prior trends in districts that received equivalent resources but were not required to reduce class size. I use the same comparative interrupted time series design to compare schools that were differentially affected by the policy (in terms of whether they had to reduce class size) but that did not receive equal additional resources. The results from both the district- and school-level analyses indicate that mandated CSR in Florida had little, if any, effect on cognitive and non-cognitive outcomes. Thirteen tables are appended: (1) Effect of Required CSR at District Level on District Characteristics; (2) Effect of Required CSR at School Level on School Characteristics; (3) District-Level Models with Additional Years of Pre-Treatment Data (Effects in Student-Level Standard Deviations); (4) District-Level Estimates that Condition on Prior-Year Controls (Effects in Student-Level Standard Deviations); (5) District-Level Analysis Robustness Checks (Effects in Student-Level Standard Deviations); (6) Effects of District-Level CSR on FCAT Scores (Student-Level Standard Deviations), Standard Difference-in-Differences Specification; (7) Effects of District-Level CSR on Stanford Achievement Test (SAT) Scores (Student-Level Standard Deviations); (8) Achievement Effects of District-level CSR by Subgroup (Student-Level Standard Deviations); (9) Effects of District-Level CSR on Non-Cognitive Outcomes; (10) School-Level Estimates that Condition on Prior-Year Controls (Effects in Student-Level Standard Deviations); (11) Effects of School-Level CSR on FCAT Scores (Student-Level Standard Deviations), Standard Difference-in-Differences Specification; (12) Achievement Effects of School-Level CSR by Subgroup (Student-Level Standard Deviations); and (13) Effects of School-Level CSR on Non-Cognitive Outcomes. (Contains 3 figures, 21 tables and 32 footnotes.)