Purpose The purpose of this paper is to outline key findings from a contemporary review of the international empirical literature focused upon teacher leadership. It synthesises what is currently known about the nature, practice, conditions and impact of teacher leadership and to outline patterns in the contemporary empirical research base. Design/methodology/approach This review is based on an analysis of 150 empirical articles published in Scopus/SSCI-indexed journals between January 2003 and December 2017. Findings The paper draws upon this contemporary knowledge base to explore: contextual and methodological patterns of teacher leadership research; definitions of teacher leadership; and evidence on the enactment of teacher leadership, factors influencing teacher leadership and impacts of teacher leadership. Originality/value This paper highlights the progress and issues of the empirical research on teacher leadership since 2003 and identifies gaps in the knowledge base as well as areas for future scholarly enquiry.