His main research interests concentrate on children with developmental disabilities and significant communication disorders. Within this population, he is particularly interested in interventions based on augmentative and alternative communication (AAC) and assistive technology (AT). His current research investigates the efficacy of AAC and AT through systematic reviews and intervention studies using single-subject research designs. The knowledge gained from these efficacy studies is used to promote evidence-based practice (EBP) in communication disorders and special education. Another strand of his research is concerned with multicultural and cross-linguistic aspects of AAC, especially those related to symbol acquisition in culturally and linguistically-diverse learners.