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.

Significant barriers exist to accessing early ASD-specific interventions, including long wait times due to limited system resources (e.g., insufficient funding to meet caseload, lack of sufficient skilled workforce), exacerbated by restrictions to in-person care associated with families' distance from service centres, and now COVID-19 isolation measures.

In response to system pressures and COVID-19 restrictions, the investigators adapted an evidence-based in-person program (the Social ABCs) to increase efficiency and access. Adaptations included (1) abbreviating the duration of the program to 6 (from 12), (2) developing a group-based delivery approach for didactic content, and (3) providing 1:1 coaching over a virtual platform (Zoom for Healthcare). The program builds on an evidence-based in-person model that uses direct in-the-moment coaching to help parents learn skills to support their toddlers' development. The Social ABCs is considered a naturalistic, developmental, behavioural intervention (NDBI), with a focus on child motivation, play-based learning, and shared enjoyment between caregiver and child.

This three-year, multi-site project uses a randomized control trial (RCT) design to evaluate an innovative early intervention program for toddlers with confirmed or suspected autism spectrum disorders (ASD) or related social communication challenges. This study will evaluate whether this innovative virtual group-based approach (VG-Social ABCs) yields child and parent gains compared to an active control condition. The research team will enroll 120 families, recruited from Ontario, Nova Scotia, and Alberta. Toddlers (aged 12 - 42 months), with identified social communication concerns (or a confirmed diagnosis of ASD), and their primary caregiver will be randomized into one of two conditions: (1) VG-Social ABCs or (2) the active control condition. Families randomized into the control condition will have the option to receive the VG-Social ABCs training once their participation in the control phase concludes. Outcome measures include toddler social communication indices and parent implementation fidelity (both derived from video-coding), parent-reported self-efficacy and wellbeing, and child-level social communication outcomes based on parent-report questionnaires.

Analyses will be conducted at the end of the trial. Hypotheses include increased gains (from Time 0 to Time 1) in parent - and child-related variables for families in the Treatment condition, compared to Controls. Investigators also anticipate that child- and parent-related gains will be maintained at Time 2 (i.e., no significant change from Time 1) for the Treatment arm.

The research team developed the virtual model in rapid response to the COVID-19 pandemic, and pilot data shows that this promises to be a powerful way to support families of toddlers with ASD at a developmental stage when they are most amenable to intervention. Beyond COVID-related isolation measures, there continues to be a significant need for increased access to evidence-based early intervention for toddlers with confirmed or probable autism, as many families are currently waiting on years-long waitlists for service. The research team hopes to demonstrate the efficacy of this feasible and resource-efficient intervention to encourage government decision-makers to fund this program for families, leading to increased access to intervention early in life, and improved outcomes for toddlers with ASD and their families. This model will also increase access for families who live in remote and rural regions who often have difficulty accessing important interventions, both within Canada and beyond.

Inclusion Criteria:

• ability to comprehend and communicate in English
• access to high-speed internet for virtual participation
• a confirmed diagnosis of ASD made by a qualified professional, or expert clinician impression of red flags for autism spectrum disorder (ASD) or related social communication challenges
• born between 36 and 42 weeks' gestation
• birthweight >2,500g
• no neurological, genetic, or severe sensory or motor conditions
• willing to limit other interventions to 1-hour per week max. if randomized to Treatment Group
• consent to collect video recorded data
• live within the boundaries of clinical supervisors supervision requirements (Ontario, Alberta or Nova Scotia)

Exclusion Criteria:

• failure to meet inclusion criteria