This article deals with a little-known aspect of employer unionism, i.e. the personnel management strategies of state-owned enterprises and their impact on collective bargaining. Drawing on a large corpus of archive material, it focuses on the case of the employers’ organisation for Italian state-owned enterprises (1958-1998). This case is used as a prism through which attempts to regulate the relations between trade unions and state-owned enterprises are viewed. These attempts led to the formation of a kind of occupational branch, governed by its own rules and codes of conduct, which nevertheless managed to influence collective bargaining practices at national as well as branch and/or company level. The analysis of the interactions between political actors, managers and unionists shows configurations that cannot be reduced to a single model of public sector unionism. The latter was built and remodelled over the years, distancing itself from private sector unionism in several respects: the role of the state-employer in integrating trade union strategies with economic policy objectives; the expression of industrial compromise within firms through the incorporation of more general concerns into personnel management techniques; the incentive for collective actors to cooperate at multiple scales.