This study addressed the effects of Strategies for Teaching Reading, Information, and Vocabulary Effectively (STRIVE), a distributed professional development (PD) model designed to help teachers implement reading comprehension and vocabulary practices in fourth grade social studies classes. Schools (n = 81 schools, n = 235 teachers, n = 4,757 students) were randomly assigned to one of three conditions: researcher-supported PD, school-supported PD, or business as usual (typical instruction). Findings revealed significant effects for both treatment conditions when compared to the business-as-usual condition for content knowledge (g = 0.51-0.55), vocabulary learning (g = 0.49) and reading comprehension in content (g = 0.16-0.26). Statistically significant effects were not observed for the Gates MacGinitie Reading Comprehension (g = 0.04-0.06), however, the effect size for the Gates MacGinitie Vocabulary test was statistically significant for the school-supported PD group (g = 0.03-0.07). Findings establish the efficacy of the STRIVE PD model on student reading outcomes and supports the efficacy of using more sustainable methods of PD that feature school supported follow up PD. Fidelity did not mediate any outcomes. [This is the online version of an article published in "Journal of Research on Educational Effectiveness."]