AbstractMethods for assessing animal neurobehavior following prenatal/perinatal exposures have been in use for almost 20 years and screening tests incorporating them are regulated in three settings: in Japanese Segment II and III studies on drugs, European (EEC/UK) Segment I studies on drugs, and American neurotoxicity studies on chemicals.The methods used in the West for assessing behavior in these contexts at present are described in detail. The evolution of the methods over time, the concepts of apical tests and functional domains, the use of positive control agents, what the U.S. Collaborative Study has shown us, and justification for assessing animal behavior in predicting outcome from human exposures are discussed.