Virtual Group Social ABCs - Multi-site Randomized Controlled Trial

The goal of this randomized control trial is to test the efficacy of the Social ABCs 6 week, group-based model using a virtual delivery platform. The Social ABCs is a caregiver-mediated early intervention program, aiming to increase child skills in directed, intentional vocalizations, and shared smiling with a primary caregiver for toddlers identified as early signs or a confirmed diagnosis of autism spectrum disorder (ASD), or having related social communication challenges. A positive RCT was previously completed using the program's in-person individual, 12-week model, and a pilot study showing preliminary promise of the virtual group-based model has also been published. This adaptation to a virtual, group-based model maintains the core components of the intervention, but allows caregivers to meet and discuss the content as a group from their home environments and complete the program in a shorter timeframe. The main questions it aims to answer are: * Is the Social ABCs virtual group-based model an effective early intervention program for toddlers aged 12-42 months with probable or confirmed ASD, or experiencing social communication challenges, when compared to an active control condition? * Can primary caregivers of these toddlers achieve implementation fidelity in the Social ABCs intervention strategies using the 6-week virtual delivery model? Participants will be randomized into the treatment condition (A) where they will receive the Social ABCs virtual group-based intervention or, into a Control condition (B), where they meet virtually with other caregivers in the control groups over the course of 6 weeks, viewing and discussing 3 didactic presentations around general child development content (not autism- or Social ABCs-specific). Video and questionnaire data will be collected before (Time 0) and after (Time 1) the 6 week period. After an additional 6-8 weeks, the same data will be collected from both groups as a follow-up time point (Time 2). Researchers will compare the Treatment group and the Control group to measure change in the target behaviours for the child, the caregiver's use of strategies, as well as caregiver stress and self-efficacy, across time-points.