Despite the significant amount of existing research examining the relationship of follower-related factors with leadership outcomes, there is no systematic, critical review that integrates and helps leadership scholars make sense of this rapidly growing body of research. To address this gap in the literature, we first briefly discuss the leading perspectives explaining the role of followers in leadership. Next, we identify and discuss the most frequently studied theoretical narratives explaining the relationship between follower-related predictors and leadership outcomes. Because theoretical arguments generally make causal claims, we identify and examine how methodological concerns including power analysis, multicollinearity, and endogeneity might prevent researchers from supporting those claims. We further explore how these concerns, when relevant and unaddressed, might affect the reported effect sizes. We provide recommendations to help meaningfully structure the field and seed conversations for theoretical and methodological advancements in research on the role of followers in leadership.