The Mexican collection of the International Institute of Social History is substantially smaller than that of Argentina or Brazil. Of this, the collection of periodicals constitutes the principal part. This latter collection (Sections A and B) covers the period ±1880-1940. Although many items represent only a single or limited number of issues of a given publication, the total amount of information is considerable. The pre-revolution period is represented by only a restricted number of literary and positivist magazines, besides a few copies of workers' magazines from Mexico City, Orizaba, and Monterrey. The more important part of the collection, however, is formed by the periodicals of local chapters of the Casa del Obrero Mundial from the years 1912-18, such as Ariete, Redención Obrera, Revolución Social, El Sindicalista, and Tribuna Roja. In addition, there is some material relating to the I.W. W., the C.R.O.M., and the later C.T.M.