Teamwork skills are considered essential in a work environment characterized by diversity and interdependence. Consequently, middle grade teachers arrange cooperative learning so students can acquire experience with solving problems in groups. Teachers also acknowledge that they are frustrated because appropriate instruments are lacking to track student progress and detect learning needs within the social context. A resulting question is: How can teamwork skills and deficits of students be more accurately detected and fairly reported? This presentation describes an instrument to synchronize how teamwork is assessed in classrooms with the way teamwork is evaluated at the workplace. The Teamwork Skills Inventory relies on peer observation and self-evaluation to establish student accountability, acknowledge competencies, and identify learning needs of individuals, teams, and classes. Middle grade students (N = 297) including 39 in special education were administered the Teamwork Skills Inventory after 4 weeks of cooperation in inclusive teams. The peer and self-evaluation ratings of general education students and special education students were compared to determine teamwork skills and deficits for both groups. Results showed special education students rated themselves as demonstrating more teamwork skills than were observed by their general education teammates. Both groups rated the general education students as demonstrating the most teamwork skills. Considerations for improving teamwork skills are recommended to general education teachers, special education teachers, middle grade students, and parents.