This article reports findings from an impact study of a 2-year postsecondary academic program offered in state prisons. Outcomes examined for participants during their 1st year of participation include performance on a standardized test of critical thinking skills, credit acquisition, achievement motivation, educational aspirations, personal development, and institutional (prison) climate. A cluster randomized design was used in which prisons in six states were randomly assigned to implement the Correctional Education Association College of the Air (CEA/COA) program or control programming. Analyses show that students in the CEA/COA program had average critical thinking scores that were about three fourths of a point lower, as measured by the Collegiate Assessment of Academic Proficiency (effect size = -0.14), and acquired on average approximately two fewer credits (effect size = -0.43) than students from control sites after 1 year. There were no significant group differences associated with educational aspirations, achievement motivation, personal development, and institutional climate measures.