Background: A number of studies have contemplated aspects of cooperative learning that might emerge from a unit of sport education [Dyson, B., L. L. Griffin, and P. Hastie. 2004. "Sport Education, Tactical Games, and Cooperative Learning: Theoretical and Pedagogical Considerations." "Quest" 56 (2): 226-240; Dyson, B. P., N. R. Linehan, and P. A. Hastie. 2010. "The Ecology of Cooperative Learning in Elementary Physical Education Classes." "Journal of Teaching in Physical Education" 29 (2): 113-130]. None to date, however, has looked empirically at the influence sport education may have on individual team member accountability and other critical elements of cooperative learning. Purpose: The aim of this study was to present evidence that cooperative learning (or at least its critical elements) is a potential side effect of using sport education. Participants and settings: A total of 90 students (47 boys, 43 girls, 12.42 ± 0.56 years), enrolled in the same high school in Spain agreed to participate in the study. The school administration randomly distributed the students among four different year eight classes, and the research team randomly allocated two classes to the experimental group (n = 48), and two (n = 42) to the control (comparison) group. The experiment was conducted in a non-manipulated (i.e. intact) educational context. Prior to the mid-term break, both study groups experienced the same Football learning unit conducted using sport education. After the break, both groups experienced a Basketball learning unit. However, the teacher continued to use sport education with the experimental group (group A) and adopted a traditional instructional approach with the comparison group (group B). Therefore, students in group A experienced 24 consecutive sport education lessons, while those in group B experienced 12 sport education lessons followed by 12 traditional lessons. Research design: The study followed a pre-test, post-test, quasi-experimental, comparison group design. Data collection: All participants completed a previously designed and validated cooperative learning questionnaire. Data analysis: The statistical package SPSS (version 22.0) was used. Descriptive and inferential analyses were conducted. Findings: Results showed that group A enhanced their perceptions of Interpersonal Skills, Group Processing, Positive Interdependence, Promotive Interaction, Individual Accountability, and Global Cooperation significantly more than group B. Conclusions: Cooperative learning (or at least its critical elements including global cooperation) is a side effect of using sport education. As Casey and Quennerstedt [2020. "Cooperative Learning in Physical Education Encountering Dewey's Educational Theory." "European Physical Education Review"] argued, cooperation is not learnt but is practiced over successive lessons and units. Given the real-world importance of cooperative learning and given calls to broaden the pedagogical experiences of young people [Metzler, M. W. 2011. "Instructional Models for Physical Education." 3rd ed. Scottsdale, AZ: Holcomb Hathaway], it seems important to have different approaches to help young people become more cooperative.