The purposes of this study were to generate a unidimensional sports perfectionism scale for competitive athletes, and to calibrate a 36-item perfectionism scale using the Rasch model. The instrument was administered to 208 undergraduate students (132 males and 76 females) at a university in the southeastern U.S., ranging in age from 18 to 31 yrs. Using the Rasch rating scale model, the perfectionism item difficulty and the person's level of perfectionism were estimated. Model-data fit was determined by Infit and Outfit statistics (>= 0.5 and <=1.5). Overall, the model fit the data well. One item regarding consequences and punishments for failing to meet expectations was removed from the final estimations as unrelated to perfectionism (Infit and Outfit statistics, 1.6 and 1.5, respectively). The distribution of the item difficulties (M ± SD logits; .00 ± .54) was well targeted to the participants' perfectionism levels (.04 ± .71). Calibration results indicated that the most difficult items for participants to agree with when considering perfectionism in sports were "If someone has better skills at a particular sport than I do, then I feel like I am inferior in all skills or sports." (logit = .81), followed by "I feel that I had a bad game or match if I made a mistake during the contest." (logit = .73) and "My coach rarely compliments me on my performance." (logit = .70). The least difficult items for participants to agree with when considering perfectionism in sport were related to goal setting methods: "I set higher goals for myself than most people set for them." (logit = -.90), followed by "I have extremely high goals." (logit = -.89). Participants' perfectionism levels were compared by competition level (community, high school, state, and national). One-way analysis of variance results indicated a significant difference in logits among the level of competition, F (3, 194) = 10.78, p < .001. Athletes who competed at the intercollegiate or national level demonstrated higher perfectionism than other competition levels. Rasch analysis supported the measure of perfectionism in sport as a unidimensional construct. Further investigations on validating the unidimensional sports perfectionism scale will be warranted. Keyword(s): assessment, sport topics