The nutritional status and mealtime performance among a group of children with autism spectrum disorders (ASD) were examined before and after admission to an intensive feeding day-treatment program. Treatment involved escape extinction, reinforcement, and stimulus fading procedures. Outcomes focused on dietary diversity and mealtime performance, including acceptance, swallowing, and disruptive mealtime behaviors. Upon admission, participants exhibited severely restricted diets, low rates of acceptance and swallowing, and high rates of disruptive mealtime behavior. Following treatment, significant improvements regarding food variety, consumption, and appropriate mealtime behavior were demonstrated. Gains were maintained after caregiver training was conducted and caregivers were introduced as the primary feeders.