The gender gap in college-level STEM remains a persistent issue despite increased efforts to understand and address women's disparate participation. This scholarly article uses a meta-narrative systematic review of the literature to chronicle forty years of STEM-related literature, identify longitudinal patterns and themes in explanations of the gender gap in college STEM majors, and then evaluate the extent to which these explanations have evolved over time. Based on a systematic review of 324 full texts spanning the past 40 years of scholarly literature, five dominant meta-narrative explanations emerged: individual background characteristics; structural barriers in K-12 education; psychological factors, values, and preferences; family influences and expectations; and perceptions of STEM fields. The authors then used the resulting meta-narrative system to examine and document trends both across and within meta-narratives to draw conclusions regarding how scholars, practitioners, and policy makers have conceptualized the determinants of the STEM gender gap over time. Important implications for future research and practice are drawn based upon this analysis. © 2014 by Begell House, Inc.