Background: Many young children in the U.S. spend a significant portion of their day in childcare facilities where they may be exposed to contaminants linked to adverse health effects. Exposure data on volatile organic compounds (VOCs) and particulate matter (PM) in these settings is scarce. Objective: To guide the design of a larger exposure assessment study in urban childcare facilities, we conducted a pilot study in which we characterized indoor concentrations of select VOCs and PM. Methods: We recruited 14 childcare facilities in the District of Columbia (Washington, DC) and measured indoor concentrations of seven VOCs (n = 35 total samples; 2-5 samples per facility): benzene, carbon tetrachloride, chloroform, ethylbenzene, o-xylene, p-xylene, and toluene in all facilities; and collected real-time PM measurements in seven facilities. We calculated descriptive statistics for contaminant concentrations and computed intraclass correlation coefficients (ICC) to evaluate the variability of VOC levels indoors. We also administered a survey to collect general health information on the children attending these facilities, and information on general housekeeping practices and proximity of facilities to potential sources of target contaminants. Results: We detected six of the seven VOCs in the majority of childcare facilities with detection frequencies ranging from 71% to 100%. Chloroform and toluene were detected in all samples. (author abstract)