In the last 5 years, the literature on animal-assisted intervention (AAI) for Autism Spectrum Disorder (ASD) has doubled in size from 42 studies prior to 2015 to 85 studies (cumulative total assessed in 2020). Horses remain the most commonly researched animal for AAI, followed by dogs. The most commonly researched outcome was social interaction, across 21 studies. Though the quantity of studies has increased, issues with methodological rigor remain. Results highlight the need for a continued focus on methodological rigor as well as refining the structure of animal-assisted interventions, addressing the welfare needs of the animals involved, and continuing to establish an evidence base of both significant and nonsignificant findings for AAI for individuals with ASD.