While delivering decent, affordable housing at scale is essential to global sustainable development, one formidable blockage is a lack of accessible housing finance for end users. People on low incomes have been perceived by lenders as high risk. They are excluded from financial systems and are forced to self-build using informal credit at exorbitant rates. This article engages with this problem, discussing practical examples and potential ways forward. It does so through case studies of models from Reall (a UK-based international development organization and social enterprise that promotes affordable homes) and its partner organizations in India, the Philippines, Nepal, Mozambique, and Pakistan. The article evaluates the strengths and limitations of these models and their potential for scaling up. Reall’s partners demonstrate that decent houses can be delivered at a cost that is accessible for potential low-income homeowners while proving the viability of lending to borrowers at the bottom of the income pyramid. This is essential for demonstrating the commercial viability and impactful investment opportunity represented by affordable housing in urban Africa and Asia.