This study compared parental psychiatric symptom severity, and the absence or presence of severe substance abuse, as predictors of contact with minor children for a representative sample of adults with diagnoses of serious mental illness (N = 45). Child contact and psychiatric symptom severity were measured during regularly scheduled 6-month research interviews over a total 30-month period following each participant's entry into the project. Severe substance abuse was documented as present or absent for the 6-month interval preceding each interview. Results revealed that incidence of severe substance abuse was repeatedly associated with less frequent parent-child contact, even after controlling for psychiatric symptoms, diagnosis, gender, age, ethnicity, and socioeconomic status. Neither psychiatric diagnosis nor symptom severity predicted frequency of child contact when substance abuse was taken into account. Mental health agencies offering parenting classes for adults with serious mental illness should incorporate substance use interventions to reduce loss of child custody and strengthen parent-child relationships.