BACKGROUND: Assessing the use and effectiveness of complementary and integrative health (CIH) therapies via survey can be complicated given CIH therapies are used in various locations and formats, the dosing required to have an effect is unclear, the potential health and well-being outcomes are many, and describing CIH therapies can be challenging. Few surveys assessing CIH therapy use and effectiveness exist, and none sufficiently reflect these complexities. OBJECTIVE: In a large-scale Veterans Health Administration (VA) quality improvement effort, we developed the Complementary and Integrative Health Therapy Patient Experience Survey, a longitudinal, electronic patient self-administered survey to comprehensively assess CIH therapy use and outcomes. METHODS: We obtained guidance from the literature, subject matter experts, and Veteran patients who used CIH therapies in designing the survey. As a validity check, we completed cognitive testing and interviews with those patients. We conducted the survey (March 2021-April 2023), inviting 15,608 Veterans with chronic musculoskeletal pain with a recent CIH appointment or referral identified in VA electronic medical records (EMR) to participate. As a second validity check, we compared VA EMR data and patient self-reports of CIH therapy utilization a month after survey initiation and again at survey conclusion. RESULTS: The 64-item, electronic survey assesses CIH dosing (amount and timing), delivery format and location, provider location, and payor. It also assesses 7 patient-reported outcomes (pain, global mental health, global physical health, depression, quality of life, stress, and meaning/purpose in life), and 3 potential mediators (perceived health competency, healthcare engagement, and self-efficacy for managing diseases). The survey took 17 minutes on average to complete and had a baseline response rate of 45.3%. We found high degrees of concordance between self-reported and EMR data for all therapies except meditation. CONCLUSIONS: Validly assessing patient-reported CIH therapy use and outcomes is complex, but possible.