This report presents estimates on private health insurance for 1977, based on the National Medical Care Expenditure Survey (NMCES). The NMCES obtained information on private insurance policies in force in 1977 from the employers and insurance companies of a nationally representative sample of the civilian noninstitutionalized population. A brief discussion of the financing of health care through private health insurance and the importance of employer-sponsored plans is included. A detailed description of insurance benefits of the population under age 65 in the United States is provided. Their insurance is characterized in terms of the inclusion of specific health services, the provisions of basic and major medical insurance, and the benefits applicable to expenses for a variety of health services. The distribution of insurance characteristics is described in general and in relation to group enrollment, employment, and the characteristics of insured persons. The description of private health insurance in the United States incorporates more recent data from other sources to complement the more detailed and comprehensive estimates from NMCES. Eleven summary tables, 75 tables, and 13 figures are included in the text. (Author/NB)