Int J Exerc Sci 4(4) : [265][266][267][268][269][270][271][272] 2011. Social comparison theory was used to examine if males exercising with a female research confederate posing as either attractive or unattractive would alter their exercise mood, exertion, and enjoyment. A total of 101 college students (51 males and 51 females) were randomly assigned to one of three conditions: biking alone, biking with an attractive female confederate, or biking with the same female confederate appearing unattractive. All participants were instructed to complete 20 minutes of exercise at 60%-70% of their maximum target heart rate. Standard exercise mood measures (e.g., Activation-Deactivation Adjective Check List) were administered immediately prior to and immediately following exercise. Pulse rate and exercise work load (i.e., bike speed and RPMs) were assessed throughout the exercise experience and exercise enjoyment was measured following exercise. In the attractive condition, the confederate dressed fashionably in form fitting and stylish work-out clothes and wore make-up and jewelry while the same confederate in the unattractive condition wore baggie casual sweat clothes and no make-up or jewelry. Results indicated that female participants were more relaxed while males were less relaxed when they were in the unattractive confederate condition (p < .05). However, no exertion differences emerged between experimental conditions (p's > .05). Participants reported the most enjoyment while in the control condition exercising alone and the least enjoyment in the attractive confederate condition (p < .05). Social comparison theory predicts exercise outcome such that participants report less enjoyment yet more relaxation for females but less for males when exercising with an attractive female confederate thus altering their exercise experience based on those around them.