Addressing factors that make it more likely for families to attrite from early intervention trials will allow researchers to ensure that families reap the full benefits of participation. This study was an analysis of 78 children (Mage = 18.38 months, SD = 5.78) at risk for autism participating in a university-based randomized controlled trial of two 8-week long early intervention programs. Overall, attrition through 8-weeks was low, approximately 13%, however by the one-year follow-up attrition rates were approximately 50%. The most consistent predictor of attrition was the distance that families had to travel to the university. These data highlight the importance of providing services and support (e.g., financial and logistic) during follow-up to families to maximize their participation.