This article presents a systematic review of empirical research on public sector innovation, analyzing 181 articles and books published between 1990 and 2014. The review focuses on five themes: definitions of innovation, types of innovation, goals of innovation, antecedents of innovation, and outcomes of innovation. The authors develop an empirically based framework to identify important antecedents and effects of public sector innovation and propose three future research directions: (1) increasing methodological diversity, (2) emphasizing theory development and testing, and (3) conducting cross-national and cross-sectoral studies to link different governance and state traditions with the development and effects of public sector innovation. The review highlights the need for more empirical studies, better theoretical underpinnings, and a broader focus on outcomes to enhance the understanding of public sector innovation.This article presents a systematic review of empirical research on public sector innovation, analyzing 181 articles and books published between 1990 and 2014. The review focuses on five themes: definitions of innovation, types of innovation, goals of innovation, antecedents of innovation, and outcomes of innovation. The authors develop an empirically based framework to identify important antecedents and effects of public sector innovation and propose three future research directions: (1) increasing methodological diversity, (2) emphasizing theory development and testing, and (3) conducting cross-national and cross-sectoral studies to link different governance and state traditions with the development and effects of public sector innovation. The review highlights the need for more empirical studies, better theoretical underpinnings, and a broader focus on outcomes to enhance the understanding of public sector innovation.