This article provides a systematic review of the literature on backsourcing. The aim is to synthesize existing literature in order to compare and analyze similarities and differences in backsourcing in the private and public sectors. The study asks questions about: which methods and theories have been used, why backsourcing has been implemented, and what reasons have been described for backsourcing. The study is based on an analysis of 500 articles about backsourcing and 33 articles in the final data set. The results show that backsourcing is primarily caused by: increased costs, lack of quality, and contract problems in the private sector, along with loss of control, cost saving, and changed strategy in the public sector. The study's synthesis highlights three explanations for how backsourcing is managed and interpreted in both the sectors. The article contributes specifically to summarizing current research on backsourcing, synthesizing how backsourcing has been studied, illustrating gaps in the research, as well as explaining relevant differences between private and public backsourcing.