This paper summarizes environmental investigations (n Euro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin) 458) conducted during the first 60 years of the epidemic-assistance investigation program at the Centers for Disease Control and Prevention. These investigations were grouped into 10 categories: toxic chemicals (n Euro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin) 102), indoor air quality and outdoor air toxics (n Euro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin) 21), new or rare epidemic diseases and unexplained syndromes (n Euro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin) 29), natural disasters (n Euro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin) 81), terrorism and unintentional human-made disasters (n Euro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin) 9), substance use and abuse (n Euro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin) 13), environmental aspects of infectious disease (n Euro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin) 132), those affecting neonates and infants (n Euro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin) 11), violence and injuries (n Euro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin) 51), and miscellaneous (n Euro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin) 9). Among the most important or prominent were studies of lead and arsenic toxicity at smelters, mercury in paint and beauty creams, dioxin in waste oil in Missouri, polychlorinated biphenyls and multiple other toxic chemicals, global pesticide poisoning outbreaks, hepatic angiosarcoma among vinyl chloride workers, toxic oil syndrome in Spain, eosinophilia-myalgia syndrome from contaminated L-tryptophan, diethylene glycol poisoning in Haiti, aflatoxicosis in Kenya, Gulf War illness among veterans, impact and needs assessments during natural disasters (e.g., Hurricane Katrina (2005) and the Mount St. Helens volcano eruptions (1980)), risk factors for heat-related mortality, domestic and international terrorist attacks, Parkinsonism related to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in California, and unintentional injury- and violence-related events.