Between 2015 and 2018, a university in the Mountain West region of the United States piloted a mathematics intervention supported by the U.S. Department of Education's Strengthening Institutions Program (SIP). Designed to improve outcomes of undergraduates taking Algebra and Pre-Calculus courses, the intervention applied pedagogical and delivery practices founded in self-efficacy theory and mathematics mindset utilizing peer tutors in the classroom. Using hierarchical linear modelling, we compared outcomes of SIP (n = 325) and non-SIP (n = 2727) students while controlling for teaching and classroom characteristics and student background characteristics. Students enrolled in College Algebra were three times as likely to pass if they were enrolled in the SIP intervention section (Odds Ratio = 3.1). Pre-Calculus students enrolled in the intervention had approximately the same likelihood of passing as students in traditional instruction, but final examination scores were significantly higher for SIP students. Our research suggests that the SIP intervention played a role in improving student performance in both courses. Program successes and challenges for implementation are also presented.