Most adolescents with type 1 diabetes (T1D) encounter barriers to achieving optimal glycemia, including effective planning and monitoring their T1D and problem-solving, and following through with T1D treatment decisions. Thus, the overall aim of Diabetes Journey, a randomized controlled clinical trial, was to assess the feasibility, acceptability, and preliminary efficacy of a novel, amusement park-themed, web-based mobile health (mHealth) intervention tailored for adolescents who experienced barriers to T1D self-management. Secondary aims included examining post-intervention changes in T1D health-related quality of life, T1D self-management behaviors, and hemoglobin A1c (HbA1c). This article describes the study rationale, recruitment, design, and baseline characteristics of the adolescents (aged 12-17 years) who were randomized to one of two groups: Diabetes Journey or Enhanced Standard of Care. Diabetes Journey focused on reducing challenges related to stress, burnout, time pressure, and planning through the delivery of 5-8 intervention sessions using a problem-solving framework. Enhanced Standard of Care participants attended 4 education sessions focused on similar topics through the T1D Toolkit© website (educational content and brief videos about T1D). Adolescents (N = 195) were recruited with n = 162 randomized (M