Chemical intervention during prenatal or postnatal ontogeny can result in complex biochemical, morphological and behavioral alterations in brain development. As has been shown at the conference, the knowledge of specific actions of a given drug/chemical in the adult can serve as a guide for choosing processes affected by the same compound administered during development. Commonly, however, the neuronal or glial substrates for chemical action in the developing brain are not known and cannot be easily predicted on the basis of effects observed in the mature animal. Indeed, there are a multitude of structurally dissimilar compounds that affect diverse and unpredictable targets in the developing brain. The focus of the review is to present an approach for detecting and characterizing chemically-altered brain development that can be used regardless of the information available on the chemical in question. (Copyright (c) 1989 by Intox Press, Inc.)