Traditional SRH programming has left 252 million adolescents currently with unmet need, suggesting there is room for improvement. In 2016, Population Services International’s (PSI) Adolescents 360 (A360) project began with funding from the Bill & Melinda Gates Foundation and Children’s Investment Fund Foundations, aiming to turn this model ‘inside-out’, by placing girls at the center of programming. PSI uses a transdisciplinary approach, joining adolescent developmental science, public health, socio-cultural anthropology, social marketing and human-centered design (HCD). A360 interventions are designed with girls by revisiting evidence; leading with questions, curiosity and empathy; and getting out into her world. There is a growing call among the adolescent and youth reproductive health (AYSRH) community—and beyond—for this kind of approach, one that is more responsive to clients’ needs, puts users at the center, and co-creates with them; but there is still a gap in practical knowledge and guidance about how to marry this with the way implementing organizations traditionally operate.