As management science models are developed in marketing, they make demands for more sophisticated inputs from the behavioral sciences. This is particularly true in the area of advertising media models. A continuing behavioral research program to develop estimates of repetition response functions for media models is reviewed. The program finds functions which differ importantly in level, slope and shape depending on the measure of response, market segment, product type, brand, advertising format, advertising illustration, advertise- ment color, media scheduling, ad appeal, and competitive situation. It is argued that such response function variations, found in both laboratory and field research, should be represented in media models. To illustrate this point, the results of a study of repetitive effects of one-sided (supportive) and two-sided (refutational) competitive advertisements are applied to runs of the MEDIAC planning system. Inclusion of the behavioral data produces favorable changes in MEDIAC output in terms of schedules and schedule results. The potential of further interaction between behavioral data and management science models is discussed.