Nearly half of all students in the United States are placed into at least one developmental course in college. Many of these students fail to complete developmental course sequences and persist to degree completion. First-Year Seminars are one of several high-impact practices associated with increased persistence, retention, and graduation rates of college students. Inverse probability of treatment weighting (IPTW) was used to explore the effect of concurrent first-year seminar enrolment on the academic achievement of students placed into developmental mathematics. Study results indicated that students who self-selected into a first-year seminar were more likely to earn a passing grade in their developmental mathematics course and have higher overall GPA. These results may inform strategies for integrating learning support with instruction for academically underprepared college students.