PROJECT ABSTRACT/SUMMARY Each year, over 120,000 individuals are diagnosed with end-stage renal disease (ESRD) in the United States (US). Approximately 97% of those individuals begin using dialysis as their method of renal replacement therapy. The options for dialysis in the US are in-center hemodialysis, home hemodialysis, and peritoneal dialysis. Home hemodialysis and peritoneal dialysis are considered forms of self-care dialysis (SCD), and are associated with benefits such as improved survival rates, greater control over treatment scheduling, reduced time in hospitals and clinics, higher quality of life, and financial savings. Despite these benefits, uptake of SCD has been minimal compared to in-center hemodialysis. Previous interventions and clinical recommendations aimed at improving the dialysis modality decision-making process have primarily focused on factors at the individual and interpersonal level. Our objective is to identify distinguishing individual, interpersonal, organizational, and policy factors that facilitated selection of SCD and in-center hemodialysis, and then generalize these differences in a greater sample of patients with ESRD. To do this, we will conduct a mixed- methods (qualitative and quantitative) sequential exploratory approach. We will achieve these goals with the following objectives: 1) Determine the knowledge, attitudes, and beliefs of patients currently undergoing dialysis for ESRD regarding the different dialysis options as well as the experiences with the decision-making process, using interviews with questions and prompts informed by the social ecological model, and 2) Generalize and validate the findings from Phase 1, and test hypotheses generated based on Phase 1 results, to understand dialysis modality choices using survey data from patients undergoing dialysis. In Phase 1, we will conduct qualitative interviews with a diverse population of patients undergoing dialysis, and ask them to reflect retrospectively on their experiences leading up to dialysis initiation. Results will shed light on whether patients had the opportunity and/or enough time to undergo a decision-making process, what circumstances allowed them to do so or not, and what specific personal preferences and values helped shape their decision. Additionally, these findings will inform Phase 2 hypotheses and study materials. Phase 2 will validate and corroborate Phase 1 findings using survey data in a larger sample of patients with ESRD undergoing dialysis. Pre-selected survey items will assess sociodemographic and psychological characteristics, health behaviors, clinical factors, interpersonal relationships, access to healthcare prior to ESRD and previous experiences with healthcare. In both phases, we will recruit participants from diverse racial/ethnic, regional, and socio-economic backgrounds, as well as varying lengths of time on dialysis. Outcomes from this proposal will be significant by revealing what factors and at which social-ecol...