The present study investigated the neurobehavioral outcomes of fetal cocaine exposure. Attempts were made to control, by design or statistical analysis, for significant confounders. Timing and amount of drug exposures were considered, and biologic measures of exposure were quantified to classify exposure severity. One hundred sixty-one non-cocaine and 158 cocaine-exposed (82 heavily and 76 lightly exposed) infants were seen at a mean-corrected age of 43 weeks post-conception and administered the Neurobehavioral Assessment (NB Assessment). Heavily cocaine-exposed infants had more jitteriness and attentional problems than lightly and non-exposed infants. They also had more movement and tone abnormalities, and sensory asymmetries than non-exposed infants. Heavily exposed infants were more likely to be identified with an abnormality than non-exposed infants and there was a trend toward heavily exposed infants being more likely to be identified with an abnormality than lightly exposed infants. Furthermore, there was a trend for heavily exposed infants to be less likely to be testable than non-exposed infants. After the confounding and mediating factors were considered, heavily cocaine-exposed infants were four times as likely to be jittery and nearly twice as likely to demonstrate any abnormality than lightly and non-exposed infants, but all other effects were no longer significant. Higher concentrations of the cocaine metabolites of cocaine, cocaethylene, and benzoylecgonine (BZE) were related to higher incidence of movement and tone abnormalities, jitteriness, and presence of any abnormality. Higher cocaethylene levels were related to attentional abnormalities and higher meta-hydroxybenzoylecgonine (m-OH-BZE) was related to jitteriness. Drug effects on attention were mediated by maternal psychological distress, suggesting that this factor should be considered in future studies of drug exposure effects.