The positively reinforcing and activity enhancing effects of IP cocaine (0, 5, or 25 mg/kg) were assessed at three ages (14-17, 21-24, and 28-31 days) in outbred CD-1 mouse pups treated prenatally by either oxazepam (OX, 15 mg/kg PO twice/day on days 12-16 of pregnancy) or vehicle (VEH). A 4-day unbiased conditioned place preference (CPP) procedure was used with combined visual and tactile cues (white walls and wide-mesh metal floor versus black walls and narrow-mesh floor). A single 25 mg/kg cocaine dose produced CPP in both prenatal groups of 28-31 day-old mice. At the two younger ages, a significant cocaine CPP was found in prenatal OX mice but not in vehicle animals; the latter apparently developed CPP less readily than the offspring of indisturbed dams in a previous experiment. On the other hand, prenatal OX did not produce substantial changes in the developmental profile of cocaine effects on locomotor activity, consisting of a dose-related response enhancement which is much more marked at 22 and 29 days than before weaning.