Few data are available concerning the trajectories of mental and motor development across time for cocaine-exposed children compared with others. Findings are presented from individual group curve analyses of the mental and motor development measured by the Bayley Scales of Infant Development-II (BSID-II) on repeated visits from 3 through 36 months of a group of prenatally cocaine-and-other-drug-exposed children (n = 265) compared with those exposed to no drugs (n = 129) or no-cocaine-but-other-drugs (n = 66), including alcohol and/or tobacco. Across time, there was a general decline in motor performance but cocaine-exposed-infants showed a trend toward a greater decrease than children in the other two comparison groups. For mental performance, there was also a decline across age but only through 24 months and no differences in the trajectory of the cocaine-exposed group compared to the other two. And, across all assessment ages, cocaine-exposed-infants showed lower BSID-II mental performance compared to both non-drug and non-cocaine-exposed children. Results suggest that prenatally cocaine-exposed children show delayed developmental indices, particularly in their mental performance, but their trajectories across time are similar to those from impoverished, non-cocaine-exposed groups.