This thematic and comparative analysis of more than 150 years of unionism in Australasia explores the similarities and differences in the economic and political contexts in which trade unions have sought to define themselves and represent their members. The state and employers have followed a similar path in Australia and New Zealand for much of that time, and in both cases that journey has been to the detriment of unions for the last generation. In this context, unions in the two countries have exhibited very similar patterns of union growth and decline, policy, and lines of inclusion and exclusion. This is not to say that there are no differences between context and unions in these two Tasman countries. The politics of the labour movement and the relationships between unions, peak bodies and political parties have at times been quite different, and different sorts of unions have been the most influential within each labour movement. Overall, however, the similarities between the two movements have been greater than the differences. By the early part of this century, Australian and New Zealand unions faced similar problems as their relationship with the state, the labour market and employers became much more problematic than it had been for most of their history.