Concentrations of carbonyl compounds (formaldehyde, acetaldehyde, acrolein and acetone) and BTEX (benzene, toluene and xylenes) were monitored at 128 residential homes (255) in Xicheng district, Beijing, during the period of November–December 2009. The indoor concentrations of formaldehyde, acetaldehyde, acrolein, acetone, benzene, toluene and xylenes were in the ranges of 1.3–85.6 µg/m3, 0.7–102.0 µg/m3, 0.3–102.1 µg/m3, 0.1–25.1 µg/m3, 1.0–47.5 µg/m3, 1.3–86.0 µg/m3 and 0.2–78.7 µg/m3, respectively. The concentrations of all species during the investigation period were below the Chinese guideline values. Based on the measured concentrations, a receptor model (PMF; positive matrix factorization) coupled with the source information was applied to identify the major emission sources. The results showed that four major sources were identified by the PMF method, including (1) outdoor incursion factors, (2) emissions from building materials and paint solvent, (3) emissions from particle board and plywood flooring and (4) emissions from household cleaning chemicals. Our results also reveal that the health risks due to exposure to formaldehyde and benzene for Beijing residents were greater during this period than those for people living in Guangzhou and Hangzhou, China.