Often discussed under the umbrella term “collaborative housing”, it is frequently argued that alternative housing forms are well suited to address various sustainability challenges in relation to housing and urban development. This project provides a critical and interdisciplinary assessment of such propositions, asking the question: Can alternative housing forms contribute to comprehensive sustainability goals, and what are the barriers and opportunities for this? This aim is pursued through in-depth analysis and comparison of evolving ideas and practices in Sweden and Denmark, which often are seen as countries where alternative housing forms have been pioneered and are relative successful. The project draws on historical institutionalism and path dependence to analyse historical pathways of alternative housing forms in their geographical, political and institutional contexts, identifying barriers as well as opportunities. It furthermore links this to sustainability transition research to assess the possible contributions of alternative housing forms to address sustainability goals and challenges. The purpose is to make a substantial theoretical and empirical contribution to research on alternative housing forms, and, with particular focus on Sweden, to provide policy-makers, planners and activists with means to address sustainability challenges in relation to housing.