The Insulin-only Bionic Pancreas (BP) Pivotal Trial compared the BP initialized only with body weight vs. standard-of-care (SC) . The BP autonomously determines all insulin doses. Meals are announced without carbohydrate counting. For youth aged 6-17 the mean adjusted difference of HbA1c at 13 weeks between BP and SC was -0.5% (95% CI: -0.7, -0.2, P<0.001) : percent of time <54 mg/dl was not different between groups. Focus groups with youth who used the BP and their parents were conducted at the trial’s end. Youth reported positive experiences: improved A1c, increased independence, less parent worry and texting about glucose, less family diabetes conversations, less cognitive and emotional burden, less time managing diabetes, less worries about nighttime lows, more sleep, easier mealtimes, and easier school management. Children felt parents trusted them more and parents spent less time managing glucose at night. Some reported increased lows and others less. Some found challenges with exercise while others found it managed exercise well. Some found the BP took too long to learn their body and to correct high glucose. Concerns included: not having a snack announcement, site change frequency, small insulin capacity, lack of insulin-on-board information, poor backlighting, screen timing out too fast, and not having a clip or being waterproof. Parents reported positive experiences: pride in the child’s independence, less cognitive and emotional burden, less time managing diabetes, less diabetes conversations, and better school experiences. Most reported improved sleep and easier mealtimes. Some found challenges with exercise while others found it managed exercise well. Some found improved TIR and less lows while others found more lows or delays in correcting highs. Some found the system learned their child while others felt the system struggled. Parents were concerned that the low insulin warning did not go to parents’ phones. Youth and parent perspectives highlight experiences in learning and using the BP and offer insights related to multiple psychosocial domains which can guide future innovations. Disclosure K. R. Howard: None. K. P. Garza: None. M. Feldman: None. J. Weissberg-benchell: None. Bionic pancreas research group: n/a. Funding National Institute of Diabetes Digestive and Kidney Diseases (#1UC4DK108612-01)