Compersion is a positive emotion experienced in relation to one's partner's relationship(s) with other partner(s). Experiencing it is highly desired in communities practicing consensual non-monogamy (CNM), especially polyamory. This article presents the results of a study on compersion on Polish CNM individuals. The main goal of the study was to adapt to the Polish-speaking population the COMPERSe (Classifying Our Metamour/Partner Emotional Response Scale; Flicker et al., 2021), the first standardized quantitative scale designed to measure compersion. The analyses were performed on data obtained from 211 individuals in CNM relationships and on a comparative group of 169 people in monogamous relationships. The results of the confirmatory factor analyses suggested that the three-factor model of the original COMPERSe version did not fit well, leading to further revisions that resulted in a 7-item, two-factor solution with excellent fit, excellent internal consistency, strong divergent and convergent validity, and excellent test-retest stability. The CNM individuals were found to have higher scores on compersion and cognitive empathy and were also less jealous than the monogamous participants. Furthermore, polyamorous individuals experienced more compersion and less aversion to partner's autonomy than people in open relationships. It was also revealed that compersion indirectly predicted relationship satisfaction by decreasing jealousy and that compersion was, in turn, predicted by cognitive empathy. However, when polyamorous and open relationships were analyzed separately, compersion predicted relationship satisfaction directly, but only in polyamorous relationships; meanwhile, in open relationships, satisfaction was directly predicted by cognitive empathy.