Aim To investigate the application of an expanded Transactional Stress and Coping Model for the psychological adjustment of non-chronically ill, African-American siblings of children with sickle cell disease (SCD). Methods Ninety-seven siblings (M = 11.24 years) from 65 families who care for a child with SCD participated. Primary caregivers completed the Coping Health Inventory for Parents, the Family Relations Scale and the Child Behaviour Checklist, while siblings completed the Kidcope, the Children’s Self-Efficacy for Peer Interaction Scale, and the Social Support Scale for Children. Results Family processes were predictive of sibling adjustment, revealing that family coping, expressiveness and support improved adjustment, while family conflict predicted poor adjustment. Conclusion Findings suggest that family-centered interventions stressing family expressiveness and support, while minimizing conflict, will contribute to sibling psychological adjustment.