Purpose of the review The availability of the Children's Health Exposure Assessment Resource funded by the National Institute of Environmental Health Sciences provides new opportunities for exploring the role of tobacco smoke exposure in causing harm to children. Recent findings Children of smokers are exposed to nicotine and other harmful tobacco smoke chemicals in utero as well as in their environment. This passive exposure to tobacco smoke has a variety of negative effects on children. In-utero exposure to tobacco smoke causes poor birth outcomes and influences lung, cardiovascular, and brain development, placing children at increased risk of a number of adverse health outcomes later in life, such as obesity, behavioral problems, and cardiovascular disease. Furthermore, most smokers start in their adolescence, an age of increased nicotine addiction risk. Biomarkers of tobacco exposure helps clarify the role tobacco chemicals play in influencing health both in childhood and beyond. Although electronic cigarettes (e-cigarettes) appear to be a nicotine delivery device of reduced harm, it appears to be a gateway to the use of combustible cigarette smoking in adolescents. Summary Pediatric researchers interested in elucidating the role of tobacco smoke exposure in adverse outcomes in children should incorporate biomarkers of tobacco exposure in their studies.