The paper discusses EPA's research program on indoor air quality. Now in its third year, it is a broad-based program that includes: field surveys of pollutant concentrations in homes, characterization of emissions from sources, health studies of genotoxic and irritant/neurobehavioral effects, and a limited amount of research and development of indoor air quality controls. The primary emphasis in all areas is on organic compounds, except for controls, where emphasis is on particles (although even there the orientation is partly organic, since indoor air respirable particles are mostly organic condensation aerosols). The area of greatest overall emphasis has been on a national field survey of air quality in homes. The field survey will obtain distributions of exposure estimates to indoor and outdoor air pollutants. It will help confirm whether indoor concentrations are in fact much higher than outdoor concentrations, as suggested by several small field studies that have been done to date. Research on indoor sources, health effects, and indoor air quality controls will continue to be significant components of the program. In addition, EPA's basic programs in air pollution research are likely to be increasingly influenced by indoor air quality concerns.