Until recently, there has been little published systematic empirical research into business coaching. This article reports on a systematic, critical review of 111 published empirical papers investigating business coaching theory, processes, and outcomes. The present article identifies a significantly larger body of empirical research than covered in previous reviews and uses a Systematic Review methodology (SRm) to conduct a comprehensive review of the available empirical evidence into business coaching effectiveness focusing on implications for theoretical development, practice (within human resource development) and further research in this area. This review identifies convergence around factors that contribute to perceived effective coaching practice but nevertheless highlights a number of issues to be resolved in further research. These include determining the primary beneficiaries of coaching, the factors that contribute to coach credibility, and how the organizational and social context impacts on coaching. Weaknesses in coaching research methodology and research gaps are also noted.