This paper reviews the main strands of research on employee share ownership over the last forty years. It considers research findings in the literature on types of share ownership, the incidence of share ownership plans, the ‘determinants’ of the use of share plans by companies, influences upon employee participation in share plans, the effect of share ownership on employee attitudes and behaviour, the effect on company performance, and the relationship between share ownership plans and other forms of employee participation. The paper does not provide a comprehensive review of the literature on these topics: instead it highlights the main findings that have emerged in the literature to date, and suggests some avenues for future research. It is suggested that majority worker ownership is different in character and effects from ‘mainstream’ minority employee share plans in large companies but the literature has tended to conflate the two. It is argued that future research needs to distinguish the various forms of employee share ownership if the impact of share ownership is to be more precisely calibrated.