Early intervention helps to address developmental delays in young children with autism spectrum disorder. Yet, research suggests there are barriers to enrollment into research studies that test the effectiveness of these interventions for infants at risk. This study identifies family characteristics that were associated with agreement to enroll in a clinical trial of early intervention for 12-month-old infants at risk for autism spectrum disorder. As part of a large longitudinal study, infants were evaluated for early signs of autism spectrum disorder at 1 year of age. Of the fifty-seven infants who were showing signs of autism and deemed eligible for the early intervention trial, 44% declined enrollment. Results suggest that families were more likely to decline enrolling into the intervention study if the mother was working full time, the total household income was between US$60,000 and US$100,000, and they lived further from the clinic. In contrast, infant autism symptoms and parental concern at 12 months were not significantly associated with enrollment. These findings highlight the need for intervention studies that are more accessible to parents, for example, intervention that takes place in the home, in addition to more research on how parental understanding of, and willingness to act on, early social-communication delays impact intervention study enrollment. Future research can then examine how to address these barriers to enrollment in early intervention studies. Such findings will shed light on best practices for dissemination of early identification and intervention strategies.