This study employs a potential outcomes modeling approach to estimate the causal effect of the National Math + Science Initiative's College Readiness Program on Advanced Placement test taking and qualifying score earning for three recent cohorts of schools. Results indicate substantial and significant increases in both AP test taking and qualifying score earning for all students. In addition, significant effects for AP test taking and qualifying score earning over baseline were found for female students and minority students when analyzed separately. This study provides evidence of the effectiveness of a College Readiness Program that is having a significant and important impact on preparing more students to succeed in math and science careers and improve the future of math and science education in this country.