Decisions concerning entitlement to sickness benefits have a substantial impact on the lives of individuals and on society. In most countries, such decisions are made by staff of private or public insurance organisations. The work performed by these professionals is debated, hence more knowledge is needed on this subject. The aim of the present study was to review scientific studies of the practices of social insurance officers (SIOs) published in English, Danish, Norwegian and Swedish. Studies were searched for in literature databases, in reference lists, and through personal contacts. Analyses were made of type of study, areas investigated, research questions, theories used, and the results. Sixteen studies were included. SIOs and several other actors are responsible for applying measures to minimise sick-leave and promote return to work (RTW). The studies focusing on coordination of such measures revealed that SIOs felt unsure about how to handle their contacts with clients and other actors. One study indicated that the SIOs, partly due to lack of time, accepted the recommendations of physicians instead of making their own judgments about granting sickness benefits. While all SIOs must make decisions concerning entitlement to sickness benefits on a daily basis, few of the reviewed studies scrutinised the actual granting of sickness compensation. The studies were also deficient in that they investigated the decision latitude of the SIOs from a very limited perspective, mainly on an individual level and often primarily in relation to colleagues and/or clients rather than to the laws and regulations of the sickness insurance. The concepts and framework in this area of research need to be developed to facilitate elucidation of the interaction between different actors in local spheres, professionals in different disciplines, and between welfare staff and individual citizens.