Background: Urinary stone disease (USD) imposes a major economic and health burden on the United States and the Veterans Health Administration (VHA). Current barriers to delivering optimal health care to patients with USD include the dearth of evidence-based process measures and treatments and the complexity of secondary prevention measures for USD. Significance/Impact: Current guidelines for best practice management of USD are largely based on clinical principles or expert opinion. The relative lack of evidence-based guidelines may lead to suboptimal care and drive unwanted practice pattern variability of quality of care for USD. The proposed research will address the following VHA/ORD priorities: Primary care practice and management of complex chronic diseases (such as recurrent USD) and quality measurement of USD prevention. Innovation: The proposed research will determine which guideline-recommended strategies are effective for secondary prevention of USD. Randomized clinical trials are not yet on the horizon, and so our findings hold the promise of rapidly expanding the evidence base for optimal care of USD and shift the clinical practice paradigm for USD towards primary care providers so that more Veterans with USD can receive effective stone prevention. Specific Aims: We propose the following specific aims: 1) Determine which prevention measures are associated with lower rates of USD recurrence in the VHA; 2) Evaluate how VHA providers are currently implementing prevention measures for USD; and 3) Identify current barriers to implementing effective prevention measures for USD in the VHA. We hypothesize the following: 1) prevention measures such as screening for primary hyperparathyroidism, 24- hour urine testing, and prescription of stone-related medications are associated with longer periods of time to recurrent USD and/or fewer stone events; 2) primary care providers are less likely than specialty providers to implement prevention measures for USD; and 3) each provider type face unique barriers that reduce utilization of effective stone prevention measures. Methodology: Aim 1 will identify a national cohort of Veterans with incident or recurrent USD between 2010 and 2016 and use methods that mimic randomized clinical trials to identify which guideline-recommended measures lead to longer times to a second USD event or fewer USD events. Aim 2 will examine the proportion of patients who receive care from primary care, nephrology, and urology providers following their index stone event and identify which providers are more or less likely to implement each prevention measure. Aim 3 will conduct national surveys with primary care, nephrology, and urology providers affiliated with the VHA to identify barriers to implementation of effective stone prevention measures. Next Steps/Implementation: The VHA is ideally positioned to support comparative effectiveness studies to determine which best practice guidelines are most effective at reducing USD ...