During the winter of 1935-36 the U. S. Public Health Service inquired into the state of the Nation''s health and underlying social and economic factors by means of a house-to-house canvass of over 700,000 households in urban communities in 18 States and 37,000 households in rural areas in 3 States. This paper sets forth the purpose and scope of the survey, outlines in some detail the method of sampling and canvassing, compares various aspects of the population with 1930 Census data as a rough measure of the reliability of the Health Survey sample, and records the major definitions employed in the survey. Subsequent papers will present the detailed findings.