Abstract: An improved method for authenticating articles is described. A mixture of at least two photochromic compounds that have different absorption maxima in the activated state and also preferably other different properties are incorporated into a carrier composition, e.g., ink, paint, fiber or polymer used to form the authenticating display data on the article. The authenticating display data is subjected to various steps of the authenticating method that may include preferential activation of less than all of the photochromic compounds, activation of all the photochromic compounds, preferential bleaching of less than all of the photochromic compounds, and bleaching of all the photochromic compounds. Subsequent examination of the display data following the various activation and bleaching steps by verifying means enables the article to be authenticated.