Generalizability theory explicitly recognizes that multiple sources of error and true score variance exist and that measures may have different reliabilities in different situations. Thus, it enjoys many advantages over classic true score theory; however, it is relatively little used by social science researchers outside of educational psychology. This unfortunate situation has arisen, in part, because researchers do not realize that the coefficients of generalizability, which generalizability theory produces, are reliability coefficients. Labelling these coefficients as reliability coefficients should increase interest in, and the use of, generalizability theory.