Parents and primary caregivers provide a key source of linguistic input for children early in the developmental process. The Milton and Ethel Harris Research Initiative Treatment (MEHRIT) is a developmental social pragmatic intervention that trains parents on supporting their child’s communication development. This study investigated whether MEHRIT training was associated with changes in parent language use following treatment. Preschool-aged children with ASD and their parents participated in a randomized controlled trial. Twenty-five minute parent-child interactions were videotaped pre-treatment and post-treatment, twelve months apart, and each parent utterance was assigned a code indicating its main communicative function. Parents in the MEHRIT group outperformed the control group post-treatment in the use of skills taught by MEHRIT, using a significantly higher proportion of comments and responses, as well as a significantly lower proportion of directives. Results of this study offer support for parent-implemented therapies, suggesting that parents have the potential to apply strategies obtained from coaching in the facilitation of communication with their children.