The school environment can be an important site of exposure to cat, dog, dust mite, and cockroach allergens, which have been detected in the settled dust of many schools. The sizable body of research that has been published in recent years warrants careful examination. This review article informs clinicians, researchers, and other parties about the potential for exposure in the school environment, factors that affect allergen concentrations, and areas of future research. While average concentrations in schools were usually under risk levels for symptoms or sensitization, many studies reported at least one location where the concentrations exceeded these levels. Maintenance, mechanical, and administrative factors were related to allergen levels in schools. From a clinical perspective, the school environment in industrialized nations has a lower potential for exposure than the home environment, but schools are significant for allergic individuals whose home environment has been addressed to the extent feasible. From a public health perspective, the school environment should be considered as a target for primary and secondary prevention. It can be more practical and amenable to intervene on a single school than the hundreds of homes in a community. Future research should continue to evaluate which interventions are most practical and result in the greatest measurable improvements. In addition, research should further examine the relationship between allergen exposure in schools and health effects, in order to develop an accurate exposure assessment model and risk levels that are specific to the school environment.