A Web-Based Intervention to Support the Mental Well-Being ofSexual and Gender Minority Young People:Mixed MethodsCo-Design of Oneself

Background: Sexual and gender minority youth are at greater risk of compromised mental health than their heterosexual andcisgender peers. This is considered to be due to an increased burden of stigma, discrimination, or bullying resulting in a heightenedexperience of daily stress. Given the increasing digital accessibility and a strong preference for web-based support among sexualand gender minority youth, digital interventions are a key means to provide support to maintain their well-being. Objective: This paper aims to explicate the co-design processes and underpinning logic of Oneself, a bespoke web-basedintervention for sexual and gender minority youth. Methods: This study followed a 6-stage process set out by Hagen et al (identify, define, position, concept, create, and use),incorporating a systematic scoping review of existing evidence, focus groups with 4 stakeholder groups (ie, sexual and genderminority youth, professionals who directly support them, parents, and UK public health service commissioners), a series ofco-design workshops and web-based consultations with sexual and gender minority youth, the appointment of a digital developmentcompany, and young adult sexual and gender minority contributors to create content grounded in authentic experiences. Results: Oneselffeatures a welcome and home page, including a free accessible to allanimation explaining the importance ofusing appropriate pronouns and the opportunity to create a user account and log-in to access further free content. Creating anaccount provides an opportunity (for the user and the research team) to record engagement, assess users'well-being, and trackprogress through the available content. There are three sections of content in Oneselffocused on the priority topics identifiedthrough co-design: (1) coming out and doing so safely; (2) managing school, including homophobic, biphobic, or transphobicbullying or similar; and (3) dealing with parents and families, especially unsupportive family members, including parents orcaregivers. Oneself'scontent focuses on identifying these as topic areas and providing potential resources to assist sexual andgender minority youth in coping with these areas. For instance, Oneselfdrew on therapeutic concepts such as cognitive reframing,stress reduction, and problem-solving techniques. There is also a section containing relaxation exercises, a section with links toother recommended support and resources, and a downloadssection with more detailed techniques and strategies for improvingwell-being. Conclusions: This study contributes to research by opening up the black boxof intervention development. It shows how Oneselfis underpinned by a logic that can support future development and evaluation and includes diverse co-designers. More interactivetechniques to support well-being would be beneficial for further development. Additional content specific to a wider range of intersecting identities (such as care-experienced Asian sexual and gender minority youth from a minority faith background) wouldalso be beneficial in future Oneself developments