Cohesion is crucial in software development teams, underscoring its importance in strengthening team performance and productivity. Cohesion is a process that leads the connections among team members to pursue a common goal and therefore, several factors impact their degree making its measurement not an easy task. This paper has a twofold purpose. First, to explore the main factors that affect the undergraduate development team’s cohesion, 193 undergraduate students who developed software projects were interviewed, through a conducted analysis 11 main factors that contribute to team cohesion were identified. Second, although there are instruments to measure team cohesion, the singularity of software development teams requires determining its own instrument. Therefore, several statements based on the 11 aforementioned factors, were analyzed and evaluated for internal consistency and reliability validation. As a result, an 18-item instrument to measure cohesion in undergraduate software development teams is here proposed.