Researchers have confirmed that students' motivation is one of the most important factors educators can target to improve learning (Williams & Williams, 2011). This study explored the role which student's motivation played in the retention of first-time, full-time freshman (FTFTF) STEM majors at University (U) (blinded). Student motivational assessment was used to inform interventions for improving their college success. The research included 36 participants in a program at U, called FirstSTEP. FirstSTEP is designed to improve the mathematics success of FTFTF STEM majors with Math ACT subscores of 19-23, which are mostly below the ACT benchmark for college readiness in mathematics. ACT's data suggests that students must have a Math ACT of 22 or higher to have a 75% chance to earn an A, B or C in college algebra (ACT, 2015) The FirstSTEP program focuses on mathematics preparation as an initial step in helping STEM majors improve their success in college. Participants start the program before their freshman year by attending a two-week Mathematics Summer Bridge (MSB), which refreshes students' algebra skills needed for precalculus, demonstrates connections between science and mathematics, and introduces them to components of college life. During the MSB, the students' motivation for success in their STEM major was assessed using the Science Motivation Questionnaire II (SMQ-II) authored by Glynn et al. (2011). The SMQ-II measures students' motivation on five levels: intrinsic motivation, self-efficacy, self-determination, grade motivation, and career motivation. The students' motivation scores were compared by race and gender. The participants' SMQ-II scores were compared to the scores of students in the Glynn et al. (2011) study. The FirstSTEP participants scored higher than the science majors in Glynn's research in all levels of motivation except for self-determination. To further understand how our students' self-determination perceptions related to their success in their chosen STEM majors, an instrument known as the Digital Metaphor (Rowlett, 2013) was used. Additionally, the participants' progress in their STEM majors was monitored and compared to that of a matched control group. Based on their precalculus semester grades, FirstSTEP participants were successful at a higher rate than a matched control group (81% to 73%, respectively). The freshman to sophomore STEM retention rate of FirstSTEP students was 48% compared to 34% in the control group. FirstSTEP participants, who were provided with additional academic and motivational support, had higher grade point averages, better grades in precalculus, and higher freshman to sophomore retention rates in their STEM major.