The present research examined in two studies the role of passion for refereeing in referees' affective and cognitive functioning during games. In line with past research on the dualistic model of passion (Vallerand et al., 2003), Study 1 (n1=90 and n2=148) revealed that harmonious passion (HP) for refereeing was positively associated with positive emotions and the experience of flow during games. Conversely, obsessive passion (OP) for refereeing was unrelated to positive emotions and flow, but was positively associated with negative emotional experiences during games. Study 2 (n=227) examined referees' affective and cognitive functioning after having committed an important mistake. Results showed that HP was negatively associated with maladaptive affective and cognitive functioning after a bad call, whereas OP was positively associated with such maladaptive functioning, including subsequent poor decision making. In addition, in both studies, most referees reported to be passionate toward refereeing. Finally, results from both studies remained the same after controlling for referees' gender, age, years of experience, and types of sports.