Houston is known for its lack of Euclidean-style zoning, but the city still has various ordinances that control land use. In 1998, Houston reformed its subdivision rules to allow for parcels smaller than five thousand square feet citywide. In this paper, we discuss the unique land-use rules in place in Houston prior to reform and the circumstances that led to reform, including the “opt out” provisions, which mediated homeowner opposition to substantial increases in housing density. We then analyze the effects of reform. After relief from large lot requirements, post-reform development activity was heavily concentrated in middle-income, less dense, underbuilt neighborhoods.