The proliferation of urban slums is duein large part to obsolete regulatory, legal andinstitutional frameworks at the local level governing landuse, development standards, land registration and titling.These regulations are often exclusionary, insisting ondevelopment norms and standards that are outside the realmof the poor to pay and subdivision procedures are often overburdensome, leading to informal land subdivision, thusexcluding the possibility to register titles under such"illegal" conditions. Likewise, well intentionedfederal or national housing policies that focus on theprovision of complete housing packages (as opposed toproducts like sites and services, progressive housing ordemand, rather than supply-side subsidies) often have theunintended effect of filtering-up to higher income groups,especially when private mortgage market alternatives are notavailable to middle and lower-middle class households.Reforming these structural problems remains one of thegreatest challenges, but progress is being made in countrieslike Brazil, Mexico on both the land and housing sides, andin Venezuela with regard to land and development standards.