3-5 MO. OLD FEMALE SPRAGUE-DAWLEY RATS WERE TRAINED TO RUN IN AN ALLEY TO MALE INCENTIVE RATS. ESTROUS FEMALES WERE COMPARED WITH DIESTROUS CONTROLS TO ASSESS THE OVERALL MOTIVATIONAL EFFECT OF ESTRUS. THE INCENTIVE MALES WERE EITHER SEXUALLY AGGRESSIVE OR PASSIVE SO THAT SEXUAL AND SOCIAL REINFORCEMENT COULD BE DISTINGUISHED. ESTROUS FEMALES RAN CONSISTENTLY FASTER THAN THEIR DIESTROUS CONTROLS, BUT SHOWED NO BETTER PERFORMANCE RUNNING TO ACTIVE THAN TO PASSIVE MALES. IT IS CONCLUDED, THEREFORE, THAT MATING DOES NOT REINFORCE INSTRUMENTAL BEHAVIOR IN THE FEMALE RAT. (PsycINFO Database Record (c) 2006 APA, all rights reserved)