Operation STEM (OpSTEM) is an NSF grant-funded program at Cleveland State University to improve retention and graduation among high-risk students seeking STEM degrees by supporting them through early mathematics. OpSTEM focuses on students from underrepresented minority (URM) groups, first-generation college students, and women. The OpSTEM program has two levels of treatment: supplemental instruction and a comprehensive program. This study considers URM students and their non-URM counterparts. For non-URM students, the majority of gains are seen in pass rates with supplemental instruction. The comprehensive program is associated with increases in pass rates such that URM students are indistinguishable from their non-URM counterparts. For URM students, a comprehensive program is associated with a narrowing of the achievement gap that is not found with supplemental instruction alone.