Researchers in the field of instruction are exploring the theory that different instructional procedures may be used for students with varying aptitudes so as to individualize teaching, so-called aptitude-treatment interactions (ATI's). This paper reviews pertinent literature, then seeks to develop theoretical models for the generation of aptitude-treatment hypotheses for general teaching situations. Three models are discussed. In the remedial model, the instructor attempts to provide some missing, but necessary building-block of knowledge, by identifying a specific deficit. In the compensatory model deficiencies are not corrected, but circumvented so that subsequent learning may take place. The third model involves preferential treatment which seeks to capitalize on other talents of the students to countervail any learning deficit. (RB)