The paper gives results of consultations by participants in the U.S. EPA's Indoor Air Engineering Research Program with a panel of key researchers and planners within government, industry, and academia to help identify priority program areas for indoor air research. Program elements including chemical source characterization, bioresponse testing, air cleaning, ventilation, biocontamination, cost/indoor quality modeling, and pollution prevention were ranked. The ranking was compared to existing program priorities and program recommendations were developed for use in program strategic planning sessions. A significant recommendation resulting from the process was to consider a major expansion of investigations into factors that influence growth and dispersion of biocontaminants.