Metastatic lung cancer patients experience significantly greater psychological distress (i.e., depression, anxiety) compared to other cancers. Psychological distress is as a prognostic indicator for worse clinical outcomes and poorer overall survival in cancer patients. Due to their historically poor prognosis, patients with metastatic lung cancer are often excluded from psychosocial intervention protocols. Existing interventions do not address factors that contribute to elevated psychological distress in these patients, including managing high physical symptom burden (fatigue, dyspnea, pain), regulating challenging emotions (shame, guilt, fear), and tolerating uncertainty about the future. Dialectical behavioral therapy (DBT) is a transdiagnostic, evidence- based psychotherapy that teaches participants a core set of behavioral skills (distress tolerance, emotion regulation, mindfulness, interpersonal effectiveness) to cope more effectively with emotional and physical symptoms. DBT skills training has been adapted for a variety of clinical populations and has demonstrated efficacy in reducing psychological distress. To date, DBT skills training has not been evaluated in patients with metastatic lung cancer, who stand to benefit immensely. We anticipate DBT skills training will need to be adapted to increase acceptability and relevance in patients with metastatic lung cancer, including 1) delivery, 2) dose, and 3) materials. The proposed study seeks to adapt and pilot test DBT skills training for patients with metastatic lung cancer using the ADAPT-ITT framework. Participants will be metastatic lung cancer patients who score >3 on the NCCN distress thermometer. Phase I aims to use focus groups and interviews with key stakeholders (metastatic lung cancer patients (N=20), thoracic oncology providers (N=6), clinicians with expertise in survivorship and behavioral symptom management (N=6)) to determine if and how DBT skills training must be modified for implementation with metastatic lung cancer patients. Adapted material will be reviewed by topical experts in DBT and implementation science. It is hypothesized that these activities will produce a manualized, adapted DBT skills training protocol for metastatic lung cancer patients (DBT-MLC). Phase II aims to pilot test DBT-MLC to assess feasibility, acceptability, and examine pre-to-post intervention outcomes. It is hypothesized that participants will report improvement on primary (psychological distress, i.e., depression and anxiety) and secondary outcome measures (fatigue, dyspnea, pain, emotion regulation, tolerance of uncertainty, DBT coping skill use). This project meets the National Cancer Institute's priority research area of cancer survivorship, and involves innovative adaptation of an evidence-based intervention for an underserved cancer population. Positive findings would rapidly inform the next step of research, conducting a phase 2b randomized efficacy trial comparing DBT-MLC to a control c...