[Source: Wight, R. D., & Davis, S. F. (1992). Division in Search of Self: A History of APA Division 2, The Division of the Teaching of Psychology. In A. E. Puente, J. R. Matthews, and C.L. Brewer (Eds.). Teaching Psychology in America: A History (pp. 365-384). Washington, DC: American Psychological Association.]
Officially, the American Psychological Association agreed on a divisional structure in 1944, but inaugurated them in 1945. The Society for the Teaching of Psychology began its existence simply as Division 2 (Teaching of Psychology). The divisions of General Psychology and the Teaching of Psychology received divisional numbers 1 and 2 because (a) they were the least specialized of the divisions and (b) might represent individuals who did not easily fit into more specialized divisions (Wight & Davis, 1992). The initial membership count was under 50, peaked at about 2,600 in 1976, and has stabilized, it appears, at slightly over 2,000 or so members. This current count does not include the growing number of members who have joined the Society as "affiliates," that is, nonmembers of the American Psychological Association. The total number of members of all types, including high school teachers and post-secondary teachers approaches 4,000.
The original designation of the Society as least specialized might be questioned at this point. Although the Society tries to serve teachers in all environments and therefore shows many facets, the existence of a highly successful divisional journal and the clear presence of divisional activities at the annual convention of the American Psychological Association suggest that teaching of psychology involves specialization that incorporates its own body of research and its own body of practice.