The Scott catalog is a catalog of postage stamps put out by Scott Publishing Co, a subsidiary of Amos Press . It is updated annually, and lists all the stamps of the entire world in six large volumes (as of 2002). The numbering system used by Scott to identify stamps is dominant among stamp collectors in the United States.

The first Scott catalog was a thin 21-page pamphlet with the grand title Descriptive Catalogue of American and Foreign Postage Stamps, Issued from 1840 to Date, Spendidly Illustrated with Colored Engravings and Containing the Current Value of each Variety. It was published in September 1868 by J.W. Scott , an early stamp dealer in New York, and purported to list all the stamps of the world, with prices for each. The fine print of the inside does caution the excited would-be buyer that "it is simply impossible for any one to always have every stamp" in stock.

In subsequent years, the Scott company gave up dealing in stamps, but continued to publish the catalog, gradually providing more and more detail as the hobby evolved and collectors became more sophisticated. In addition to the factual information about the stamps, the catalog also includes price information which is based on market analysis and reported sales from the previous year. As of 2002, and despite annual changes to save space, the catalog was over 5,000 pages.

The Scott numbering system is copyrighted, and the company regularly acts against anyone who uses it without permission in any way other than to publish price lists.

As the dominant catalog in the US, Scott editors have great influence over what is and is not considered to be a valid postage stamp. For instance, in the 1960s the countries of the United Arab Emirates issued many stamps that were likely never actually on sale in a post office, so Scott does not list them. One must go to a Michel catalog , for instance, to see them described. The lack of a Scott listing, though, means that most American dealers will simply refuse to traffic in such stamps.

Similarly, Scott does not list most stamps from countries embargoed by the US government, or in some cases lists them but with no prices. To some extent, this is unavoidable, since the ban on importation means that Scott's editors are unable even to acquire copies of the stamps to be described. Moreover, since US dealers and collectors are unable to buy the stamps legally, they unlikely to have any need of the data. (Again, interested persons typically use Michel instead.) The policy changes with government policy; stamps of North Vietnam recently reappeared in Scott after an absence of some years.

The dominance of Scott is such that US collectors know many of the numbers by heart, and dealers need only mention the number in their price lists. For instance, "C3a" is instantly recognized as the Inverted Jenny.

The original catalog has been reprinted, and is generally available.