Background/Aim: Sensory-based interventions, including sensory integration therapy (SIT), are one of the most highly requested and provided services for children with autism spectrum disorders (ASDs). Although SIT is predominantly provided by occupational therapists, other service providers, including speech-language pathologists, are expected to understand and, on occasion, are requested to integrate SIT into their treatment. The purpose of this study was to determine whether: (a) SIT improved the communication skills of children with autism, specifically spontaneity, complexity of utterance, and engagement; (b) effects continued following the provision of SIT; and (c) effects were consistent across young children with autism with different learning profiles. Methods: A single-subject applied behaviour analysis design was implemented to assess the effectiveness of SIT on verbal spontaneity, grammatical complexity (measured through mean length of utterance) and engagement in four young children with ASD, measuring each area before, during and after SIT. The effects of sensory integration intervention were measured by comparing each participant's expressive language and engagement in a no-treatment phase (A phase) to those same skills in the treatment phase (B phase). Findings: All of the participants performed best in the occupational therapy or post-occupational therapy conditions for spontaneity, complexity of utterance, and engagement, and the worst in the pre-occupational therapy condition. Specifically, the greatest percentage of spontaneity was noted post-SIT, with the longest measured length of utterance during SIT, and the greatest engagement found both during and post-SIT. The pre-SIT condition consistently ranked as the lowest for all dependent measures. Conclusions: Results from this small study indicate that the SIT condition (occupational therapy) yielded better communication and engagement than the condition immediately prior (pre-occupational therapy); therefore, specific components of SIT need to be examined, particularly issues of motivation and momentum.