CREW consortium represent a diverse national sample of children and families recruited over the past 30 years into 12 early life and birth cohort studies that focused on asthma. The total combined study population is 8,985 at the time of birth. The study population is quite diverse in terms of current age (ages <1 through 36 years), date of recruitment (1980-2017), race/ethnicity, and risk of asthma. There is considerable variation in the geographic locations of participants, with representation from East Coast (Baltimore, Boston, New York City), Midwest (Cincinnati, Detroit, Madison, Marshfield), South (Nashville, St. Louis) and West (Tucson). Most children are healthy (control population) while some have asthma or some form of allergic disease.