It has been more than 40 years since the Vietnam War ended and there is little recent systematic knowledge of how Veterans of the Vietnam Era (1961-1975) have fared with regard to their overall health, lifestyle factors, and aging. This epidemiologic study, called the Vietnam Era Health Retrospective Observational Study (VE-HEROeS) will provide information about the health and well-being of Veterans of the Vietnam Era to Veterans and their families who have questions about the long-term health effects of service during the Vietnam War, to clinicians who care for Veterans and lack sufficient evidence to explain health conditions, and to the VA healthcare system in order to improve VA healthcare and anticipate future healthcare needs. The main objective of this study is to determine if the overall health of Veterans of the Vietnam War and Vietnam Era, with a special focus on neurologic conditions and hepatitis C infection, is different from that of their counterparts who did not serve in the military. Exploratory aims of the study are to determine if the investigators can obtain a sample of Blue Water Navy Vietnam Veterans (who served exclusively in deep coastal waters off of North or South Vietnam) and use the survey to describe their current health, and to determine the prevalence of Veterans who attribute health conditions of their descendants to their own military service, especially conditions potentially transmitted epigenetically. The study design is a survey, with hepatitis C and neurologic conditions validated by medical record review. The questionnaire includes both validated scales and new items about physical and mental health, exposures, and lifestyle. There are two versions of the questionnaire: one for Veterans of the Vietnam Era and one for those selected from the U.S. general population who have never served in the military. The questionnaires are as similar as possible, with the exception of questions about military service, exposures, or experiences that are either removed or modified in the non-Veteran questionnaire because they do not apply to this population.