Background: VA enrollment has been extended to OEF/OIF/OND Veterans for a minimum of five years, and as a result, enrollment has grown sharply. Unprecedented proportions of these newer enrollees are Reservists or National Guardsmen returning to or finding jobs with private health insurance. Their capacity to use both VA and private sector care is unparalleled among Veterans under 65, and studies suggest that roughly half may be dual users. Dual use of health care systems raises several concerns, including discontinuity in care, duplicative treatments, and increased costs, but few studies have examined potential adverse outcomes of dual use. Because obtaining private insurance claims information is difficult, no studies have comprehensively examined dual use and associated outcomes among VA enrollees younger than 65 who have private insurance. Knowledge of dual use patterns could substantially enhance efforts to achieve three of Secretary Shinseki's top priorities: 1) strengthening access for rural Veterans, 2) expanding health programs for women Veterans, and 3) improving the quality, access, and value of mental health services. The proposed study will advance our understanding of how younger Veterans in rural states use VA, the private sector, or both systems for particular services and needs, and whether dual use is associated with benefits or risks. Objectives: Quantify the extent of VA, private sector and dual health care use among VA enrollees with private insurance, determine associations between dual use and demographics such as gender, urban-rural residence, distance to care, illnesses and health system factors, and evaluate differences in quality of care received by dual users compared to single system users, such as receipt of recommended treatments for post traumatic stress disorder and occurrences of therapeutic duplication or redundant procedures (e.g. high-cost imaging). Methods: We will assess comprehensive utilization patterns of VA enrollees with private health insurance who are younger than 65 and living in four states from 2001 through 2010 (available years vary by data source). We will obtain non-VA claims data from Wellmark BCBS of Iowa and South Dakota, and from the New Hampshire and Maine All Payer Claims Databases. Under a method we have applied previously, VA's National Data Systems (NDS) will provide each of the non-VA data sources with identifiers for all enrollees living in the state at any time during relevant years; the sources will use the identifiers to search for matching records, along with a non-reversible unique ID (UID). Matching records will be sent to NDS with the UID for each patient, but without SSNs or birthdates. The UID will be the only identifier the investigators will receive, but it will enable them to detect dual users without compromising sensitive patient information. Data elements will include demographics, inpatient and outpatient claims (including diagnosis and procedure codes) and pharmacy data; Poisson and logistic regressions will be used to compare VA-only, private sector-only, and dual users on utilization rates, receipt of recommended, quality care, occurrences of avoidable admissions and readmissions, and duplicative care related to medications and imaging, controlling for urban-rural residence, distance to care, gender, VA priority status, diagnostic categories, and types of medical services.