Nine participants outlined findings in the area of neurobehavioral effects of dioxin-like compounds and presented plans for new studies. Neurobehavioral effects are among the most sensitive and well studied toxicity end points for this class of compounds. A focus of the workshop was presentation of designs for major new studies in human populations outside the United States that are intended to extend and clarify the results of two previous large-scale studies in populations in Michigan and North Carolina. Improved methods for exposure assessment and more focused approaches to understanding specific neurobehavioral deficits were highlighted. Animal studies and in vitro mechanistic studies are emphasizing the importance of alterations in neurotransmitter systems and thyroid function that may underlie behavioral dysfunction. There is continuing improvement in analytical and study design methods to identify the most active congeners of PCB mixtures in the environment. These diverse studies will contribute to effective response of public health and regulatory groups to this continuing problem.