PROJECT SUMMARY In this R01 proposal, we outline a comprehensive 5-year research proposal that will support development and rigorous testing of a scalable intervention to improve integration of geriatric principles into surgical care of older adults with the goal of improving patient and care-partner quality of life from transitions into and out of the hospital around the time of surgery. This significant and innovative plan aims to improve care transitions for this high risk patient population as they are discharged home after major surgery. Background: Surgeons try to prepare and support older adults through the perioperative transitions to the hospital and back home, with variable success. Most surgeons are not fully equipped to address geriatric needs that exist among the rising number of older adults presenting to surgical attention. Addressing health outcomes that older adults prioritize when considering surgery is an important opportunity to improve surgical care quality in this growing patient population through development of novel interventions. Specific aims and research design: We aim to develop the first version of myPOSH, a digital intervention to improve the care of older patients undergoing surgery including development of content and application with methodology for implementation through 1) interviews with older adults undergoing major surgery and their care-partners when available (up to n=30) (Aim 1.1), with additional input from 2) key clinical stakeholder focus groups (i.e., surgeons, geriatricians, and nurses) (n=4; at least 24 clinicians) (Aim 1.2). Next, we will examine the preliminary feasibility and acceptability of myPOSH via an open pilot (n=20 patients, n=2 surgical teams across 2 sites) with exit interviews and pre-post assessments. myPOSH will be refined (Aim 2). Finally, we will examine the feasibility and acceptability of myPOSH versus usual surgical care (n=84 patients; 42 patients per arm) in a pilot RCT following predetermined benchmarks (Aim 3). These findings will inform a hybrid efficacy trial through future funding with plans to extend this work to other surgical clinic sites. Relevance: This R01 is in line with the goal of this funding announcement to develop scalable interventions to improve care transitions among high risk patient populations. Impact: As surgeons with expertise in surgical systems change, we recognize the critical need to improve surgical care quality among older adults transitioning home after surgery. Experiences gained through this proposal are foundational to future research to improve caregiver preparedness and reduce patient anxiety in the perioperative setting.