Background: Empirical evidence demonstrates that conduct disorder (CD) symptoms tend to cluster into covert and overt domains. We hypothesized that overt and covert CD symptoms may be distinct constructs with distinct risk factors. An important risk factor for CD is maternal smoking during pregnancy. We further investigated this association, attending to overt and covert CD symptom subtypes. Also, we tested whether gender and socioeconomic status (SES) modified this association. Method: Participants were male and female adult offspring (n = 682) of a community sample of pregnant women followed longitudinally from prenatal life to age 22. Prospective assessments of maternal smoking during pregnancy were used to predict self-reported DSM-III CD symptoms. Results: Prenatal exposure to smoking was significantly associated with increased overt CD symptoms for participants of low SES, but not for participants of high SES, whereas covert CD symptoms were not associated with prenatal exposure. Gender did not significantly modify the relationship between maternal smoking and CD symptom subtypes. Conclusions: These results suggest that the previously documented association between maternal smoking and CD may be specific to overt CD symptoms, providing support for the heuristic value of differentiating overt and covert CD symptoms as distinct syndromes. These findings further support smoking prevention programs for pregnant women.