Research has demonstrated that caregivers' use of intervention strategies can support their children's social engagement and communication. However, it is not clear to what degree caregivers must master the strategies to effectively support gains in social communication, specifically, core challenges such as joint attention language (comments). Twenty-two minimally verbal school-age children with autism received a social communication intervention with caregiver coaching. Through 10 min caregiver-child play interactions at eight time points, significant increase were found in children's spontaneous language. Further, children's spontaneous language was associated with caregivers' implementation. Minimum benchmarks for caregivers' total intervention implementation are discussed.