Children and youth with Autism Spectrum Disorder (ASD) often struggle to regulate their emotions, and many experience comorbid mental health issues such as anxiety and depression. Though it is not a diagnostic marker of ASD, poor emotion regulation may significantly impair daily functioning for individuals with the disorder. Nevertheless, interventions targeting emotion regulation are primarily designed for older children and adolescents with ASD. There is a critical need for early interventions that foster emotional modulation in young children with ASD and prevent long-term mental health issues. Parent-mediated interventions are often used to successfully treat core features of ASD, and likewise may be effective in addressing emotion dysregulation. This study is a pilot investigation of the Regulation of Emotional Lability in Autism Spectrum Disorder through Caregiver Supports (ReLACS) intervention, when implemented with parents of preschoolers with ASD. Weekly intervention sessions will teach parents how to support effective emotion regulation using specific techniques, and to tailor intervention using principles of behavioral analysis. A multiple probe design will evaluate intervention effects across 5 dyads. It is predicted that ReLACS will increase parents� use of strategies to support emotion regulation and reduce dysregulated emotion in their children with ASD. The investigation will also assess parent perceptions of intervention acceptability and effectiveness.