Use of illicit and licit drugs during pregnancy is a major public health concern, as it can have adverse effects on the developing fetus. Infants born of women addicted to narcotics, cocaine, alcohol, or polydrugs often undergo a characteristic withdrawal syndrome and may have physical, behavioral, and/or neurological abnormalities. As it is not feasible to ascertain whether these functional changes in human infants are produced by abused substance(s) per se or by a combination of complex socioeconomic factors and polydrug use, researchers in recent years have developed and utilized various innovative animal models to assess drug-induced alterations and their biological mechanisms during the developmental period under a controlled environment. To promote interdisciplinary communications as well as to assess the progress and the future needs in this area, the National Institute on Drug Abuse (NIDA) held a technical review at which biomedical researchers discussed their current findings in various physiological systems. This report summarizes the major findings and the methodological and experimental issues discussed at the conference. The meeting was held in Washington? DC, on May 25 and 26,1994. o 1995 Wiley-Liss, Inc.* Address reprint requests to Pushpa V.