OBJECTIVES: To assess contributions of individual lifestyle changes on systolic blood pressure (SBP) changes. METHODS: We examined associations between lifestyle behavior changes and SBP after 6 and 18 months in 782 PREMIER trial participants. RESULTS: In multivariate models omitting weight, predicted SBP reductions ranged from (1)/2 to 1(1)/2 mm Hg for reduced urinary sodium, improved fitness, and adherence to the DASH diet (except sodium at 18 months). With weight included, only fitness change additionally predicted SBP at 18 months. CONCLUSIONS: Several lifestyle behavior changes are important for BP lowering, but are difficult to detect when weight is included in multivariate models.