The U.S. Standard Atmosphere Supplements, 1966 was prepared in response to a need for atmospheric tables depicting conditions other than the mid-latitude mean represented by the tables of the U.S. Standard Atmosphere, 1962. Tables of typical winter and summer conditions for various latitudes are provided for the troposphere, stratosphere, and mesosphere. The models merge into three sets of boundary conditions at 120 kilometers in the lower thermosphere. Models starting from these boundary conditions then branch upward into atmospheric profiles which are related to the wide range of conditions in the heterosphere associated with varying solar activity, geomagnetic activity, and zenith angle of the sun. The substance of this publication is two major sets of tables: those for the region below 120 kilometers, keyed to seasonal and latitudinal variations; and those for 120 to 1,000 kilometers, keyed to solar and geomagnetic activity and solar angle. These two sets of tables, though separated, have mutual boundary conditions so that users will be able to select for any location, season, and solar activity the appropriate continuous profiles from the surface up to 1,000 kilometers. Profiles of atmospheric properties for any orbital or re-entry trajectory can thus be estimated. In addition, this publication contains information on diurnal variations in density up to 90 kilometers, refined analytic expressions which can be used to represent pressure and density profiles of the 1962 Standard and these Supplementary Atmospheres to 80 kilometers, and a mid-latitude ozone model up to 50 kilometers.