Environmental allergens are major triggers for pediatric asthma. While children's greatest exposure to indoor allergens is in the home, other public places where children spend a large amount of time, such as school and day care centers, may also be sources of significant allergen encounters. The purpose of this article is to describe schoolroom allergen levels from 3 different geographic sites obtained from dust samples collected in the fall and in spring. Environmental dust samples were collected from elementary schools in Birmingham (AL), Detroit (MI), and Houston (TX), from 4 room locations, including the cafeteria, library, upper grades, and lower grades. Samples were assayed for dust mite (Dermatophagoides pteronyssinus and Dermatophagoides farinae), cat (Felis domesticus), and cockroach (Blatella germanica 2) allergen levels. Allergen levels varied by geographic location and type of schoolroom. Schoolroom settings differed by the type of flooring (hard and carpet), room characteristics and use (food service, library shelves with books, and general classroom with multiple types of materials [individual desks and different types of furniture]), and the average age of the schoolroom dwellers (younger vs. older children). Dust mite, cat, and cockroach allergens were present in all schoolrooms and all sites at varying levels by season and by type of room. Schools may be important sources of direct allergen exposure and reservoirs that could potentially contribute to allergic sensitization and disease exacerbation in children. Further studies are needed to carefully examine the environmental allergen load in schools and its effect on children.