The prevalence and morbidity of allergic disease and asthma in the industrialized world has increased significantly in recent decades. Exposure to indoor allergens produced by dust mites, furry pets, rodents, cockroaches, foods and molds is a major driver of asthma morbidity and allergic sensitization. In recent years, multiple research studies have highlighted the role of exposures to allergens as well as other factors in determining health outcomes of allergic individuals, and indicate that the causal relationship between exposure and health effect may be far more complicated than previously assumed. This presentation will provide a summary of relevant findings of the newest peer-reviewed studies of allergen and endotoxin exposures, health effects of allergen exposure itself, as well as co-exposures with environmental pollutants and endocrine disruptors. Topics addressed will include latest results of the CDC’s National Health and Nutrition Examination Survey (NHANES), and other epidemiologic surveys conducted in schools and homes, occupational exposures in laboratory animal facilities and other work environments. The second part of the presentation will focus on effective allergen avoidance and remediation measures, to provide better tools and knowledge to the IEQ practitioner.