This study attempts to collect more comprehensive data about the indoor environmental quality in urban dwellings with schoolchildren in Beijing, China. For this purpose, indoor air temperature, relative humidity and the levels of indoor chemical and biological pollutants in 14 households were measured in 2013. Results show that, in cold winter, indoor relative humidity was often lower than the comfort limit of 30%, while indoor CO₂ concentration was often higher than the acceptable level of 1000 ppm in poorly ventilated homes with high occupant load. Indoor PM_2.5 pollution was very severe with the highest level of 523 µg/m³ in living room and 345 µg/m³ in children’s bedroom in winter. Compared with the recommended thresholds, the levels of indoor volatile organic compounds and carbonyl compounds in most homes were low. Cigarette smoke is an important indoor source of PM_2.5, formaldehyde, acetaldehyde, acetone and benzene. Also, there are significant correlations between the concentration of total volatile organic compounds and other compounds (acetaldehyde, acetone, benzene and toluene). Furthermore, two phthalates: di (2-ethylhexyl) phthalate and di-n-butyl phthalate were frequently detected in house dust. Penicillium, Cladosporium, and Aspergillus were predominant fungi in indoor air. The fungal pollution levels in different seasons and rooms were also compared.