The purpose of this study is to examine the effects and predictive power of the Diagnostic Assessment and Achievement of College Skills (DAACS) on student success. DAACS is a no-stakes, open-source, formative assessment tool designed to measure newly enrolled college students’ reading, writing, mathematics, and self-regulated learning (SRL) skills, and provide them with feedback and resources to enhance their functioning and success. A randomized control trial was performed at two online colleges (n = 17,687) to measure the effects in terms of academic achievement and credit acquisition. Predictive power of DAACS on student success were also examined. Results highlights the importance of using DAACS as a suite of assessments and supports, and not as isolated components.