Consistent with national trends, only about ½ of students who intend to major in STEM disciplines at Maryville College (MC) complete bachelor's degrees in these fields. The Scots Science Scholars (S[superscript 3] ) program was funded through the National Science Foundation's STEM Talent Extension Program to increase the number of students graduating with STEM degrees from MC. The S[superscript 3] program enrolls college freshmen who have an interest in STEM majors and math ACT scores between 21 and 27, with emphasis on students from groups underrepresented in STEM and first-generation college students. The program consists of a summer bridge, a living-learning community, early engagement in STEM research, a seminar series that exposes students to STEM careers and research fields, academic support through a first-year seminar class, peer tutoring, and time-management counseling. The program has enrolled 6 cohorts of students (n = 97) since 2013, (54% female, 22% underrepresented minorities and 35% first-generation college students). From 2013-2017, S3 compared favorably to the general college population: 96% of all S[superscript 3] completed the first year of college, 69% declared STEM majors, and 85% returned to the college for a second year (compared to 71%, p < 0.001). Overall, S[superscript 3] students persist at the college longer than non-S[superscript 3] students (P<0.01). Compared to a matched control group, S[superscript 3] had significantly higher STEM major declaration rates (68% vs. 38%), higher rates of STEM retention through the junior year (41% vs. 20%), and improved overall college persistence ( P< 0.01). Students report high levels of satisfaction with the summer program. At the end of the summer program, students report gains in skills and attitudes that are important for success in STEM. They also perform significantly better on math and chemistry assessments after completing the program. College-wide, the number of students enrolled in STEM majors at Maryville has increased by 52% since the inception of S[superscript 3], and STEM undergraduate research productivity has increased markedly. Our data suggest the S[superscript 3] program is an important component of institutional changes that are increasing the STEM population and building a robust and productive STEM culture at a liberal arts college.