Group performance has been an important topic as evidenced by an extensive literature review that has supports a positive relationship between group cohesion and performance. Social network researchers have also found similar relationships between cohesion and group performance using social network density as a proxy for cohesion. The traditional cohesion construct is measured using an attitudinal instrument that relies on member perceptions that are aggregated at the group level. The density construct, on the other hand, is based on social network relations which are based on behaviors and actual member interactions and relationships. Considering these differences, although both cohesion measures have been shown to predict group performance, it is important to understand their subtle differences in order for leaders to accurately understand how to influence each. A study of 672 students in 48 groups provided empirical evidence supporting a positive relationship between task cohesion and performance, while also a negative relationship was found for social cohesion and friendship network density relating to performance. Results also indicate a significant relationship between group cohesion and social network density suggesting that social network density could be used as a proxy for group cohesion.