The development of computer controlled telescopes at small observatories has dramatically increased the demand for and potential usefulness of astronomical catalogs in machine-readable form. The compilation and storage of catalogs containing program and standard stars are obvious necessities for the operation of an automatic telescope, but to date most observers have been collecting their own data and manually entering them into microcomputer disk storage. (This is clear from the small number of machine catalogs distributed by the ADC to smaller observatories.) Astronomical data centers located in several countries around the world currently archive, maintain and disseminate a wide variety of machine catalogs in virtually every discipline of astronomy, and these facilities can provide observers with nearly any kind of data needed for controlling telescopes (positional catalogs), reducing data (catalogs of all types of photometry, spectroscopy, etc.) and providing access to fundamental quantities needed for the interpretation of observations (catalogs of binaries, variables, radial and rotational velocities, etc.). The ADC presently has approximately 450 machine catalogs in its archives and these are available to observatories upon request. Procedures for obtaining data from the ADC and policies for distribution are described in this paper, while a list of all catalogs available can be obtained by contacting the ADC.