ImportanceMany health care systems offer adolescents access to health information through online patient portals, but few studies have explored how to engage adolescents in using and benefiting from online portals.ObjectiveTo determine how US children’s hospitals have attempted to encourage adolescent portal use, barriers to engaging adolescents, and ideal future goals for engagement.Design, Setting, and ParticipantsThis qualitative study performed structured qualitative interviews with informatics administrators from children’s hospitals across the US between February and July 2022. Informatics administrators were employed by US health care systems that managed a children’s hospital with at least 50 dedicated pediatrics beds. Data analysis was performed from November 2022 to January 2023.Main Outcomes and MeasuresThis study used thematic analysis of (1) current steps that health care systems had taken to engage adolescents in using their online patient portals and (2) barriers to engaging adolescents and ideal future goals and outcomes of engagement.ResultsAmong 58 total interviews with 65 informatics administrators who represented 63 hospitals across 58 health care systems, 6 themes of approaches to engaging adolescents in portal use were identified: (1) promoting and educating adolescents about portal enrollment, (2) establishing workflows to support enrollment, (3) seeking and incorporating feedback, (4) creating a culture or environment supporting engagement, (5) increasing portal utility, and (6) limited efforts. Barriers to engaging adolescents in portal use related to either (1) stakeholder investment, interest, and capabilities or (2) intersecting technical, ethical, and legal factors. Participants identified 4 ideal future efforts to engage adolescents: (1) develop adaptable private means of communication with adolescents, (2) use adolescent-centric user design, (3) enhance promotion and education about portal use, and (4) simplify and adapt workflows to encourage enrollment. Participants described 3 ideal outcomes of this future engagement: (1) provide education about current health, (2) prepare for transition to adulthood, and (3) improve digital health education of adolescents.Conclusions and RelevanceIn this qualitative study of informatics administrators, children’s hospitals across the US were found to have varying degrees of efforts to engage adolescents in using their portals. Most of these efforts focused on supporting adolescent enrollment, but fewer efforts focused on making the portal useful and interesting to adolescents.