The importance of organisational centralisation in determining the behaviour of trade union movements and associations of employers has been widely acknowledged, at least since Ross and Hartmann (1960) identified it as a key variable for predicting levels of industrial conflict. Since the 1970s several researchers working within the theory of neo-corporatism have demonstrated the significance of this variable, as an aspect of corporatism, in accounting for the differential behaviour of various national union movements (Bruno and Sachs, 1985; Cameron, 1984; Crouch, 1985; Garrett and Lange, 1986; Hibbs, 1978; Korpi and Shalev, 1979; Newell and Symons, 1986; Paloheimo, 1984; Schmidt, 1982; Shott, 1984; Tarantelli, 1986). The publication of Olson’s The Rise and Decline of Nations (1982) provided such arguments with an elegant theoretical base in the theory of collective action, through his concept of encompassing organisations.