Allen, NicholasLind, Monika2024-03-252024-03-252024-03-25https://hdl.handle.net/1794/29281The sensitive period of adolescence facilitates key developmental tasks that equip young people to assume adult roles. Adolescence features important strengths, like the need to contribute, and some risks, like vulnerability to the onset of mental ill health. Adolescence increasingly occurs online, where existing in-person dynamics and new affordances of digital technology combine. Online help-seeking suits the needs and preferences of adolescents, and online peer support capitalizes on adolescent strengths. The success of online peer support communities for self-injurious thoughts and behaviors (SITB) may depend on the balance of social support and social contagion in these communities. In this study, we investigated adolescent help-seeking and peer support for SITB online. We used topic modeling, machine learning classification, and multilevel modeling in pursuit of three aims. In the first aim, we discovered the topics that characterized help-seeking expressions of over 100,000 posters who chose to post in the “Self Harm” category of an online peer support platform. In the second aim, we measured the amount and type of social support provided in over a million comments in response to these posts. In the third aim, we tested whether the topics of help-seeking expressions predicted the presence and type of social support provided. The over-arching goal of these aims was to help inform policy and guide the design of online spaces to support healthy adolescent development, especially amongst adolescents experiencing mental health challenges. From the first aim, we learned that adolescents seek help online for serious problems and suffering. From the second aim, we learned that their peers provide social support most of the time, but this social support often lacks specificity and elaboration. From the third aim, we learned about the power of help-seeking expressions focused on “hopeless suicide,” “self-harm abstention,” and “hiding self-harm” to elicit social support. Across all three aims, we learned that platform design matters, and platform designers can do more to support healthy development. Adolescent online help-seekers need help that makes them feel connected. Academic researchers and corporations must work together to help young people help each other.en-USAll Rights Reserved.AdolescenceDigital mental healthHelp-seekingPeer supportElectronic Thesis or Dissertation