Complementary and reciprocal interactions are a defining feature of sibling relationships for young children. However, the social and communication difficulties of children with autism spectrum disorder (ASD) can make reciprocal play more difficult and play between siblings can be less rewarding. Sibling play can serve an important role in intervention and family cohesiveness, but there is no consistent method for involving siblings in intervention benefitting the sibling dyad. This study evaluated a novel treatment package including training siblings on play strategies to increase positive sibling play in combination with a sibling support group to offer social support for the neurotypical sibling (NT). The effects of the treatment package on NT sibling play and fidelity of implementation of naturalistic play strategies was examined using a concurrent multiple-baseline design across six dyads, five of whom completed the intervention. After behavior skills training, all NT siblings increased the number of strategies they used, and increased the frequency of initiations towards their sibling with ASD. In addition, the percentage of reciprocal play between siblings increased. Generalization probes and follow-up probes demonstrated above-baseline levels of performance across most dyads, indicating that the skills learned generalized across other toys and were maintained over time. Only three of the sibling support group sessions were completed due to the COVID-19 pandemic. Although the effectiveness of the sibling support group cannot be determined, social validity questionnaires suggest siblings and parents valued and liked the support group.