This article presents a systematic review of 181 articles and books on public sector innovation published between 1990 and 2014. The review investigates five themes: definitions of innovation, innovation types, goals of innovation, antecedents of innovation, and outcomes of innovation. Based on this analysis, the authors develop an empirically based framework of potentially important antecedents and effects of public sector innovation. They suggest three future research directions: (1) more variety in methods, including surveys, experiments, and multi-method approaches; (2) emphasis on theory development and testing; and (3) more cross-national and cross-sectoral studies. The review finds that most studies focus on qualitative methods, with a lack of quantitative studies and mixed-method studies. Innovation is often weakly conceptualized, with a focus on internal-driven, administrative process innovations. Outcomes are often not reported, limiting understanding of the effects of innovation efforts. The review also highlights a lack of clear theoretical underpinning in the studies, with few referring to existing theories. Environmental antecedents, such as political and public demands, are often associated with public sector innovation. However, the importance of these antecedents relative to others is not always clear. The authors suggest that future research should focus on cross-national and cross-sectoral studies, as well as on the relationships between innovation types, antecedents, and outcomes. They also emphasize the need for more theoretical development and testing, as well as the use of a wider range of methods in public administration research. The review concludes that public sector innovation is often seen as a value in itself, with a focus on the process of generating or adopting an innovation rather than its outcomes. The authors also highlight the need to better understand the role of political authority in shaping and influencing public sector innovations.This article presents a systematic review of 181 articles and books on public sector innovation published between 1990 and 2014. The review investigates five themes: definitions of innovation, innovation types, goals of innovation, antecedents of innovation, and outcomes of innovation. Based on this analysis, the authors develop an empirically based framework of potentially important antecedents and effects of public sector innovation. They suggest three future research directions: (1) more variety in methods, including surveys, experiments, and multi-method approaches; (2) emphasis on theory development and testing; and (3) more cross-national and cross-sectoral studies. The review finds that most studies focus on qualitative methods, with a lack of quantitative studies and mixed-method studies. Innovation is often weakly conceptualized, with a focus on internal-driven, administrative process innovations. Outcomes are often not reported, limiting understanding of the effects of innovation efforts. The review also highlights a lack of clear theoretical underpinning in the studies, with few referring to existing theories. Environmental antecedents, such as political and public demands, are often associated with public sector innovation. However, the importance of these antecedents relative to others is not always clear. The authors suggest that future research should focus on cross-national and cross-sectoral studies, as well as on the relationships between innovation types, antecedents, and outcomes. They also emphasize the need for more theoretical development and testing, as well as the use of a wider range of methods in public administration research. The review concludes that public sector innovation is often seen as a value in itself, with a focus on the process of generating or adopting an innovation rather than its outcomes. The authors also highlight the need to better understand the role of political authority in shaping and influencing public sector innovations.