There has been controversy about the relative importance of trade unions, employers, and the state in determining the development of national collective bargaining in the twentieth century. This analysis of the provincial bus industry suggests that historians underestimate the importance of trade unions in this process at their peril. The article examines the negotiating strategies both of unions and employers over the period 1934-47. Large numbers of provincial bus company workers were organised by unions in the 1930s. Two unions represented the overwhelming majority of provincial bus company employees - the Transport and General Workers' Union (TGWU) and the National Union of Railwaymen (NUR). Despite tensions between them, the unions worked effectively together to improve working conditions and wages. The tactic of using settlements of the municipal bus workers as benchmarks for provincial bus company workers was followed with notable success. The unions were able to limit widespread unofficial strikes in 1947 and harness them to their advantage. The employers in contrast were divided in their approach. British Electric Traction consistently opposed national bargaining but the independent firms and Tilling eventually supported it. The national conditions agreement of 1947 therefore owed its existence much more to the unions than it did to the employers.