Large-scale longitudinal investigation of health system change and its effects on people. The Health Tracking Household Survey is the successor to the CTS Household Surveys which were conducted in 1996-1997, 1998-1999, 2000-2001, and 2003. Also contains the Health Tracking Physician Survey. Although the HTHS questionnaires are similar to the CTS Household Survey questionnaires, the HTHS sampling design does not have the community focus intrinsic to CTS. Whereas the CTS design focused on 60 nationally representative communities with sample sizes large enough to draw conclusions about health system change in 12 communities, the HTHS design is a national sample not aimed at measuring change within communities. Hence, Community was dropped from the study title. Like the CTS Household Surveys, HTHS collected information on health insurance coverage, use of health services, health expenses, satisfaction with health care and physician choice, unmet health care needs, usual source of care and patient trust, health status, adult chronic conditions, height and weight, and smoking behavior. In addition, the survey inquired about perceptions of care delivery and quality, problems with paying medical bills, use of in-store retail and onsite workplace health clinics, patient engagement with health care, sources of health information, and shopping for health care. Domestic partners are included in the same (family insurance unit) FIU since many health insurance policies now cover them. Previously in the CTS Household Surveys, domestic partners (same-sex partners and other unmarried partners) formed separate FIUs.