Purpose: This article compares outcomes of a family-based prevention program from its original in-person mode to an online mode in response to the COVID-19 pandemic. Celebrating Families!™ is designed to improve parenting skills, family functioning, and family relationships to break the cycle of substance use problems. Method: This mixed-methods, quasi-experimental study compared outcomes of in-person and online treatment conditions and content analysis of open-ended responses to a satisfaction survey. Results: Both groups showed improvement in outcomes, with moderate effect sizes and high satisfaction. Average scores of the online groups were generally lower than the in-person scores. Qualitative data yielded participants’ accounts of improvements in parenting behaviors, family relationships, coping skills, and knowledge insights. Conclusions: Despite the contexts of COVID-19, findings provided evidence that such relational group interventions can be feasibly administered online and can effect changes required to break the cycle of substance use problems and adverse family experiences.