The expansion of participation in unpaid work such as internships, volunteering and educationally focused work placements may constitute evidence of deleterious changes to labour markets increasingly characterized by competition, precarious work and prolonged transitions to secure employment. Unpaid work, although under‐researched, is increasingly relevant in times of ubiquitous unpaid internships and the use of volunteers in roles that would have been previously paid. Yet there remains a lack of clarity in terminology and focus across studies of unpaid work. This review article addresses this concern through two primary aims. First, we review the available literature around unpaid work setting out five themes: characterizations of unpaid work; the prevalence and underlying drivers of unpaid work; the apparent benefits of participation; the costs of participation; and regulatory and structural responses to unpaid work. Together, these themes set out a holistic interpretation of the accumulated state of knowledge in this area of inquiry including the implications for organizations, employers, higher education institutions, policy makers and unpaid workers. The second aim is to synthesise the current and emerging insights arising from the review as a matrix which delineates four distinct forms of unpaid work along two dimensions – purpose of participation and level of participatory discretion. The review and resulting matrix provides conceptual clarity around unpaid work practices that informs future research. It also raises pragmatic implications for institutional and managerial decision‐making which is cognisant of the range of risks, costs, benefits and ethical issues associated with unpaid work.