The thesis seeks to provide a deeper understanding of the dynamics of interaction between the environmental and labour movements, and the conditions under which they can cooperate and form alliances in pursuit of a sustainable development agenda which simultaneously promotes ecological and social justice goals. After developing an explanatory model of the labour-environmentalist relationship (LER) on the basis of a survey of theoretical and case-study literature, the thesis applies this model to three significant cases of labour-environmental interaction in Australia, each representing a different point on the spectrum from LER conflict to LER cooperation, during the period from 1983 to 1996. Commonly held views that there are inevitable tendencies to LER conflict, whether due to an irreconcilable "jobs versus environment" contradiction or due to the different class bases of the respective movements, are analysed and rejected. A model of the LER implicit in Siegmann (1985) is interrogated against more recent LER studies from six countries, and reworked into a new model (the Siegmann-Norton model) which explains tendencies to conflict and cooperation in the LER in terms of the respective ideologies of labour and environmentalism, their organisational forms and cultures, the national political-institutional framework and the respective places of labour and environmentalism therein, the political economy of specific sectors and regions in which LER interaction occurs, and sui generis sociological and demographic characteristics of labour and environmental actors. The thesis then discusses the major changes in the ideologies, organisational forms and political-institutional roles of the Australian labour movement which occurred during the period of the study, and their likely influence on the LER. The two processes of most importance in driving such changes were the corporatist Accord relationship between the trade union movement and Labor Party government from 1983 to 1996, and the strategic reorganisation of the trade union movement between 1988 and 1996 in response to challenges and opportunities in the wider political-economic environment. The research hypothesis is that the net effect of these changes would have been to foster tendencies towards LER conflict. The hypothesis is tested in three significant case studies, namely: (a) the interaction, often conflictual, between the Australian Council of Trade Unions (ACTU) and the environmental movement in debates around macroeconomic policy, economic restructuring and sustainable development from the mid-1980s onwards; (b) the complex interaction, involving elements of cooperation, disagreement and dialogue, between the environmental movement and the unions representing coal mining and energy workers in the formulation of Australia's climate change policies; and (c) the environmental policy and campaign initiatives of the Australian Manufacturing Workers Union to improve workplace environmental performance and promote worker environmental education. The case studies confirmed the research hypothesis in the sense that, whilst the LER tended overall towards greater cooperation in the period of the study, the Accord relationship and union restructuring process worked to slow the growth of cooperative tendencies and sustain conflict over particular issues beyond what might otherwise have been the case. The Accord relationship served to maintain conflict tendencies due to the dominance of productivist ideologies within the ACTU, and the union movement's perseverance with this relationship after the vitiation of its progressive potential by neo-liberal trends in public policy. The tripartite Accord processes institutionalised a "growth coalition" of labour, business and the state in opposition to excluded constituencies such as the environmental movement. This was partially overcome during the period of the Ecologically Sustainable Development (ESD) process, which temporarily included the environmental movement as an insider in the political-institutional framework. The long-run effects of union reorganisation on the LER are difficult to determine as the new organisational forms of unions were not in place until almost the end of the period of the study. However, in the short term the disruptive effects of the amalgamations process restricted unions' capacity to engage with environmental issues. Pro-environment initiatives by the AMWU, and cooperative aspects of the coal industry unions' relationship with environmentalists, reflected the social unionist ideology and internal democratic practices of those unions, and the influence of the ESD Working Group process, whilst LER conflict over greenhouse reflected the adverse political economy of the coal industry, but also the relevant unions' less developed capacity for independent research and membership education compared to the AMWU. The LER in all three cases can be satisfactorily explained, and important insights derived, through application of the Siegmann-Norton model. Conclusions drawn include suggestions for further research and proposals for steps to be taken by labour and environmental actors to improve cooperation.