Avoidant/restrictive food intake disorder (ARFID) is a serious and impairing eating disorder - occurring in up to 4% of adults - for which most individuals do not have access to treatment. The proposed study aims to develop and test a mobile app to scale delivery of cognitive-behavioral therapy for ARFID. Knowledge gained will contribute to the development of a clinically accessible, scalable, inexpensive treatment for ARFID, a highly impairing disorder for which there are significant barriers to care access.

Inclusion Criteria:

1. Current avoidant/restrictive food intake disorder based on DSM-5 criteria
2. Must not have completed face-to-face CBT-AR at the Eating Disorders Clinical and Research Program at Massachusetts General Hospital
3. Ability to speak, write, and understand English
4. Residence in the United States
5. Access to an internet-connected smartphone device

Exclusion Criteria:

1. Underweight status (i.e., BMI < 18.5 kg/m2)
2. Complete lack of oral intake or dependence on supplemental feeding
3. Feeding or eating disorder other than ARFID
4. Any comorbid clinically significant disorder that would require attention beyond the study treatment

6. Medical instability requiring inpatient care according to the American Psychiatric Association 2023 treatment guidelines for eating disorders 7. Medical history of intellectual disability 8. Illiteracy