Unaccompanied migrant youth, fleeing to a new country without their parents, are exposed to mental health risks. Resilience interventions mitigate such risks, but access can be hindered by systemic and personal barriers. While much work has recently addressed designing technology to promote mental health, none has focused on the needs of these populations. This paper presents the results of interviews with 18 professional/ volunteer support workers and 5 unaccompanied migrant youths, followed by three design workshops. The results point to the diverse systems that can facilitate youths' resilience development. The relationship between the youth and volunteers acting as mentors is particularly important for increasing resilience but comes with challenges. This suggests the relevance of a social-ecological model of resilience with a focus on designing technology to support the mentors in order to help them better support the youth. We conclude by mapping out the design space for mentor support.

Research increasingly shows that technology can improve access to mental health interventions. However, unaccompanied migrant youth (UMY) still struggle in accessing appropriate mental health resources in spite of their high need for mental health support. Through co-design workshops, and using the lens of the socialecological model of resilience, we explored the social-ecological factors that support or hinder UMY's use of mental health apps as resources. We identifed the strong infuence of the macro-system (i.e. resettlement policies) on the bio-and micro-systems, which in turn limits participants' abilities to use the apps. Our fndings highlight the factors specifc to each social-ecological systemincluding personal experiences, technological infrastructure and social environment-that need to be accounted for when designing technological mental health resources for UMY. This contributes: a rich description of the interplay of mental health apps with socialecological systems in which UMY are embedded; and the corresponding design considerations.

INTRODUCTION:Mental health promotion apps can promote youth mental health but fail to engage young people. Fit to young people's media preferences is known to mediate engagement. OBJECTIVES:To explore the fit of existing youth mental health apps with young people's media preferences. METHODS:A workshop with 60 youth psychologists elicits designs of digital mental health interventions. A review of 29 youth mental health apps unpacks their modality strategies. We then compare modality strategies from literature on youth mental health, media preferences and engagement, and from the experts, with strategies in current mental health apps to identify potential fit problems. RESULTS:There is a mismatch between young people's modality preferences and how youth mental health apps deliver their content. CONCLUSION:There is a need to make youth mental health promotion apps more interactive and tailorable, featuring dynamic visuals and social connectivity, to better engage youth.

The International Youth Foundation (IYF) invests in the extraordinary potential of young people. Founded in 1990, IYF builds and maintains a worldwide community of businesses, governments, and civil-society organizations committed to empowering youth to be healthy, productive,and engaged citizens. IYF programs are catalysts of change that help young people obtain a quality education, gain employability skills, make healthy choices, and improve their communities. To learn more visit www.iyfnet.org. ABOUT HILTON Hilton supports the development of the Global Youth Wellbeing Index to raise awareness about youth wellbeing and advocate for increased resources to support youth development. The Index is an important road map for the company's commitment to connect, prepare, and employ one million young people by 2019. The International Youth Foundation is responsible for the content of the Index, and it does not necessarily represent the views or opinions of Hilton. To learn more visit www.hilton.com.

Youth mental health interventions are increasingly delivered through technology. One factor which may impact engagement and adherence with these apps is how well they fit with young people using them. Yet, how well these technologies fit with requirements and preferences of young people is largely unexplored. By reviewing examples of mental health promotion apps for young people (n=29) we identified a misalignment between young people's media use and what youth mental health promotion apps provide. This presents a space to improve youth mental health technology.