The thesis examines the introduction of for-profit actors into the contemporary social housing market in England, with particular reference to the management and development of new social and affordable housing. It is an under-researched segment of social housing. The research aims to improve the understanding of how for-profit actors operate through an examination of the institutional and organisational responses in the social housing market. It conceptualises a tripartite theoretical framework, using principal-agent, institutional and organisational theory to assess the impacts that the introduction of these for-profit actors has had on the market. It will argue that for-profit actors are not new phenomena. There have been three waves of policy intervention used to introduce for-profit actors and modernise the social housing market. The latest wave, which enabled these actors to be licenced landlords, has been available since 2004, but it was only formalised by the Housing and Regeneration Act 2008. The 2008 Act opened the market up to regulated for-profit landlords and enabled them to operate and compete on a level playing field with existing not-for-profit landlords. The thesis has categorised three types of for-profit providers operating in the social housing market: legitimisers, opportunists and optimisers. It identified hybrid providers that have expanded their operations outside of the housing sector. The research also identified two types of market Disrupter operating in the broader regulated and unregulated sub-market. The first are developers that build housing and the second are subsidiaries of large international financial institutions new to the sector. During times of austerity and retrenchment of government funding, these findings propose a broader definition âsub-market price housingâ for policymakers to better describe the totality of the market. This new definition includes all the variants of housing provided using government subsidy and also those using market-led solutions. A formative research methodology was used combining document analysis, interviews with elite actors in the sector, case studies and summative interviews.