In this study, a telephone survey and supplementary mailback survey were used to collect relevant details on ventilation and indoor environmental quality in small and medium-sized commercial buildings constructed after 1978 with floor area between 1,000 and 50,000 square feet and with no more than three stories. Due to the difficulty and expense of identifying and sampling only recently constructed buildings, the sample was limited to the fastest growing counties. The survey was designed to identify a key contact who was the most appropriate individual at each building site to respond to detailed questions regarding the physical configuration and operations and maintenance of the building. A total of 476 telephone surveys focusing on building characteristics and indoor air quality and 71 supplementary surveys focusing on ventilation were completed. In general the findings were that a broad variety of air contaminant sources are present in small and medium-sized commercial buildings and that, furthermore, the building owners and managers did not know much about their heating, ventilating, and air conditioning system; the emission sources and concentrations; indoor air quality, and ventilation. The results will be used by the California Energy Commission to guide the development of future building energy design standards that protect indoor air quality and comfort in California small and medium-sized commercial buildings, by the California Air Resources Board to improve exposure assessments of indoor and outdoor air pollutants, and by both agencies to help interpret the field results obtained from a follow-up study.