Underrepresentation of some populations in STEM fields occurs because these students experience achievement gaps with performance lower on average than their overrepresented peers. Interventions to reduce achievement gaps and increase the retention of underrepresented students in STEM courses include approaches found both inside and outside of class-time, with active learning being a leading example of an in-class intervention in which didactic instruction is replaced by student-centered activities. In this investigation, student performance was examined in reformed general chemistry classes that employed student-centered active learning strategies when taught in person but employed more didactic instruction when taught online during emergency remote teaching, along with classes using traditional instruction in both modalities. In both settings, achievement gaps for underrepresented minority students in reformed courses were significantly narrowed compared to students in classes with traditional instruction, suggesting that the course structure and teaching practices beyond in-class active learning in reformed courses are significant contributors to student success.