This international comparison firstly examines labour market organization, casual labour and work mentality in North American seaports and in Hamburg. By contrast to British ports, these ports finally dispensed with casual labour between the world economic crisis and the Second World War, and labour markets there were centralized. Secondly, the industrial militancy of mobile dockworkers without permanent jobs is examined through a consideration of syndicalist organizations (1919–1921), and interpreted as an interplay of experiences with power in the network of labour market, workplace and docklands. The study refers repeatedly to the decisive dividing line between regularly and irregularly employed dockworkers. National differences in trade union representation and dispute behaviour are analysed by reference to dockworkers' direct actions.