On average, low-income students score significantly lower on the SAT than their wealthier peers, causing a cascade of disadvantages that decrease opportunities for college admission and receiving financial aid. To address this disparity, undergraduates at the University of Houston created Aspire, a service-learning project that provides SAT tutoring and postsecondary preparation to students at a predominantly Hispanic, low-income urban high school. From 2019 to 2023, 125 students participated in Aspire, attending five to 11 weekly sessions per semester for up to 22 hours of SAT and postsecondary prep mentorship. Of these students, 53 met inclusion criteria for analysis, with results showing that students in the Aspire program exhibit statistically significant SAT score improvements, with a mean increase of 54 points on a 1,600-point scale. This study demonstrates that undergraduate-led service-learning programs can improve outcomes for underserved students at a relatively low cost, offering a model for replication by other universities.