PROJECT SUMMARY/ABSTRACT This is an application for a K23 award for Dr. Shanthini Kasturi, a rheumatologist at Tufts Medical Center. Dr. Kasturi seeks to establish herself as an independent investigator of patient-centered behavioral interventions for rheumatic diseases, with an initial focus on systemic lupus erythematosus (SLE). The goal of this proposal is to develop (Aim 1) and pilot test (Aim 2) a theory-driven peer coaching intervention to reduce fatigue, a critical unmet need of patients with SLE. These research objectives are paired with training objectives to build expertise in behavioral intervention development and skills in clinical trial design and conduct. In Aim 1, Dr. Kasturi will design an intervention that targets the multidimensional components of fatigue through individualized coaching administered by trained peers with SLE. Coaches will leverage validated patient- reported outcome measures to tailor behavior change support to patients? specific drivers of fatigue. The intervention will be deployed via a mobile health application and be iteratively refined with the input of SLE patients using user-centered design methodologies. In Aim 2, Dr. Kasturi will conduct a randomized controlled pilot trial to evaluate the feasibility and acceptability of the intervention in patients with SLE. To achieve these goals, Dr. Kasturi has assembled an expert mentorship team and formulated the following training objectives: (1) to build expertise in behavioral intervention development, including health behavior theory and research methods, patient-engaged intervention development methods, and the use of mobile health interventions for behavior change; and (2) to develop skills in clinical trial design and conduct, including advanced methodologies for randomized behavioral trials and the conduct of multi-site trials. This project aligns with the priorities outlined in the NIH Action Plan for Lupus Research through its focus on fatigue, its goal of developing a behavioral intervention, and its integration of validated patient-reported outcome measures and mobile health technology to enhance the intervention. This proposal will form the basis for a future R01 to test the efficacy of the peer coaching intervention on fatigue in SLE, while supporting Dr. Kasturi?s development as a research scientist with expertise in behavioral interventions for rheumatic diseases.