The purpose of this report was to measure the effect of the Baylor College of Medicine Summer Science Institute (BCMSSI) on science performance of students whose teachers participated in the program during summer 2013. Paired t-test results showed statistically significant increases in the BCM students' Stanford 10 science performance at the third, fourth, and eighth grades. Results also showed moderate to substantively positive BCMSSCI program effect at these grade levels. Linear regression analysis indicated that students' previous year Stanford 10 science scores were the strongest predictor of science performance. Implications include additional mentoring and science support throughout the school year, and close monitoring of the instructional practices that BCMSSI teachers use in the classroom. [For the 2011-2012 report, see ED599246.]