Part of the National Longitudinal Surveys which will also examine the labor market experience over a 5-year period of women aged 30-44 and young men and women 14-24 years of age, this first report analyzes a large number of economic, social, and psychological variables. It seeks to describe and explain variations in the labor market position of the males who were between the ages of 45-59 at the time of the initial interview in mid 1966. Forthcoming annual surveys of this same cohort will allow analysis of labor market experience and behavior, including mobility, over time. Data were derived from personal interviews with a multi-stage probability sample of 5,043 males in the civilian noninstitutional population. Attitudinal measures were included in the questionnaire. Some conclusions were: (1) There is hardly a dimension of labor market behavior in which black men and white men do not differ, although these differences disappear in some cases when occupation is controlled, and (2) The presence of health problems is related to low labor force participation, high unemployment, low commitment to work, high propensity to retire, low rates of pay (even within major occupation groups), and relatively more dissatisfaction with current job. Numerous tables are included. (ET)