This article examines the changes that have taken place in the United Kingdom's residential mortgage markets since the 1980s and the specific role of mortgage-backed securitization in generating change. The authors describe the nature of securitization, its development during the boom and slump in mortgage market activity in the United Kingdom, the types of financing vehicles that have been used, and the ways the risks involved in this financing technique have been assessed, mediated and priced. The article concludes by discussing the likely development of this market in the United Kingdom.  While future developments will be heavily influenced by investors' requirements on yields and the expansion of a liquid market, funding restrictions and competition for market share among traditional mortgage suppliers, the higher return on capital achievable through securitization, and the nature of the recovery in residential mortgage business will strongly influence further issues of mortgage-backed securitization in the United Kingdom.