Background: As autistic children are being diagnosed at a younger age, the need to identify appropriate early supports has increased. Therapist-delivered and parent-mediated autism intervention may benefit children and parents. Objective: This pilot study examined developmental outcomes for autistic pre-schoolers and mental health and wellbeing outcomes for their parents (n = 53) following a 10-month intervention period. Methods: All families were accessing therapist-delivered interventions--the Early Start Denver Model (ESDM) or usual community services--and some families also received additional parent-coaching ESDM (P-ESDM). Families were assessed at 3 timepoints. Results: Overall children made significant gains in cognitive skills and adaptive behaviour, with no differences between groups. Parents overall reported increased parenting stress over time. P-ESDM conferred no added benefit for child outcomes, and similarly, no clear benefit for parent outcomes. Conclusions: Our findings suggest that children receiving early intervention make developmental gains, regardless of type of intervention, and challenges assumptions that, as an adjunct to other intervention programs, P-ESDM improves child or parent outcomes. Further research is needed to explore the effects of parent-mediated programs.