We propose to conduct a scientifically valid, descriptive survey to measure the prevalence and levels of lead in dust, soil, and paint, and the prevalence and levels of various indoor allergens in floor and bedding dust in the nation's housing stock. The survey strategy is a population-based, multi-stage area probability sample designed to represent all 50 states. The survey will include approximately 1000 homes in at least 100 primary sampling units (PSU, a metropolitan area or cluster of counties). Residents of candidate participant housing units (HUs) will initially be contacted by a letter to introduce and provide a brief explanation of the study. A field interviewer will then visit each candidate HU to screen and recruit eligible units into the study. A short Screening Questionnaire will be administered to an adult HU resident and an invitation will be extended to those HUs that are eligible to participate in the study. A field data collection visit will be scheduled for the following week, at the resident's convenience. The collection visit will be conducted by a two member team (including the same field interviewer that will conduct the screening/recruiting visit) and will consist of administration of an informed consent form and Data Collection Questionnaire, completion of home observation forms, collection of interior dust and exterior soil samples, and conduct of nondestructive paint lead analyses on both interior and exterior walls. Soil and dust samples will be shipped to analytical laboratories for lead and allergen analysis. Extensive survey design, procedure, and reporting details are provided in the National Survey Lead Hazards and Allergens in Housing: Protocol and Sample Design Report. It is anticipated that this study will provide allergen-specific data regarding: 1) housing conditions, demographic factors, and climate to facilitate evaluation of regional, ethnic, socioeconomic, and housing characteristic differences in the indoor allergen burden; 2) an estimate of indoor allergen exposure in the U.S. population; 3) baseline data that can be used as a reference point for future allergen surveys; and 4) a database that can be used to stimulate future studies which attempt to correlate allergen exposure to disease outcome. The study will yield lead hazard data to: 1) estimate the number and percent of homes with dust and soil lead levels above selected thresholds; 2) identify sources of lead in dust in housing; 3) permit future analysis of lead hazard control strategies and costs, including associated policy and regulatory guidelines.