The Early Start Denver Model (ESDM: Rogers & Dawson, 2010) is a manualized, developmentally oriented play-based intervention incorporating principles of Applied Behaviour Analysis, Pivotal Response Training and relationship-based methods. Designed for infants, toddlers and preschoolers with ASD, the crucial components include use of an interdisciplinary team to address a range of challenges including a focus on the child’s affect, attention and arousal in the teaching procedures. The efficacy of the ESDM has been documented in a randomized clinic controlled study (Dawson, Rogers, et al., 2010), in which participants aged between 18- to 30-months received an average of 15 hours a week of 1:1 ESDM intervention by trained therapists. Significant improvements were found in the ESDM group compared to the ‘treatment-as-usual’ community group, across a variety of developmental domains at the 2-year follow-up. The suite of papers in this symposium, from across the world, present findings from the next steps in development of the ESDM: extension of the ESDM to group-based delivery in a community-based setting (1) and the development of experimental measures to predict treatment outcomes in group-based delivery (2; Australia), examination of social reward on leaning (3; USA) and translation of the ESDM into an Italian context (4; Italy).