Over the past 10-15 years, many cities in the US have experienced a form of development unknown since World War II-middle-income housing in their downtown cores. Such downtown housing initiatives assume that functional interdependence among different property sectors-office, residential, retail, entertainment-will ensue and that the resultant, co-ordinated investments will produce a lively and attractive downtown environment. This article explores the impediments to this synergism using a perspective that emphasises the 'thicknesses' of property markets; that is, the social, institutional and place-specific qualities of real estate investment. New York City's lower Manhattan revitalisation plan, designed to subsidise office conversions, is used as an example.