This article provides a comprehensive and integrative review of 285 articles on servant leadership published between 1998 and 2018. The review aims to address four main issues: conceptual clarity, measurement, theoretical and empirical advancements, and future research directions. The authors offer a new definition of servant leadership, evaluate 16 existing measures, map the theoretical and nomological network of servant leadership, and propose a detailed future research agenda. They find that while servant leadership has gained significant traction in academic journals, there is still a lack of coherence and clarity in the field. The review highlights the need for more robust methods to test the empirical distinctiveness of servant leadership from other leadership theories and to explore its incremental validity. The authors recommend three measures of servant leadership behavior that have undergone rigorous construction and validation: Liden et al. (2015) SL-7, Sendjaya et al. (2018) SLBS-6, and van Dierendonck and Nuijten (2011) SL5. The review also discusses the research design used in servant leadership studies, noting the dominance of quantitative methods and the need for more experimental designs. Finally, the authors explore the antecedents and outcomes of servant leadership, emphasizing the importance of leader characteristics and the relationship between servant leadership and follower outcomes.This article provides a comprehensive and integrative review of 285 articles on servant leadership published between 1998 and 2018. The review aims to address four main issues: conceptual clarity, measurement, theoretical and empirical advancements, and future research directions. The authors offer a new definition of servant leadership, evaluate 16 existing measures, map the theoretical and nomological network of servant leadership, and propose a detailed future research agenda. They find that while servant leadership has gained significant traction in academic journals, there is still a lack of coherence and clarity in the field. The review highlights the need for more robust methods to test the empirical distinctiveness of servant leadership from other leadership theories and to explore its incremental validity. The authors recommend three measures of servant leadership behavior that have undergone rigorous construction and validation: Liden et al. (2015) SL-7, Sendjaya et al. (2018) SLBS-6, and van Dierendonck and Nuijten (2011) SL5. The review also discusses the research design used in servant leadership studies, noting the dominance of quantitative methods and the need for more experimental designs. Finally, the authors explore the antecedents and outcomes of servant leadership, emphasizing the importance of leader characteristics and the relationship between servant leadership and follower outcomes.