The Los Angeles Earthquake Hazards Reduction Ordinance, enacted in 1981 required owners of all unreinforced masonry (URM) buildings to comply with retroactive seismic standards. Among the 8100 URM buildings are approximately 1600 residential buildings with 46,000 housing units. As of March 1991, 55% are complete, 13% are in progress, 12% have been demolished and 20% have not complied. Data kept by the city shows the average cost per unit to be about $6000, and the average rent increase for tenants to be $67 per month, a 14-26% increase over pre-retrofit rents. Less than one-third of the owners completing the retrofit have applied for rent increases. Only 6% of the completed buildings have received financing assistance from the city. Two-thirds of the residential building owners appear to be finding the financing to complete the retrofit without assistance from the city but the remaining one-third of the units are at risk because owners are unable or unwilling to undertake the required work. Tenants who were forced to leave demolished or vacated units had difficulty finding replacement housing at affordable rents, and all tenants in downtown neighborhoods have been impacted by increasing rents and lost units. The Los Angeles experience is important for other cities attempting to establish ordinances and prepare policy for assisting building owners and tenants.