Transactive memory systems (TMS)–knowledge of who knows what in a group–are often measured based on their Behavioral Indicators: Specialization, Credibility, and Coordination. Though these Behavioral Indicators are frequently used to assess the strength of a TMS, they make up only one of the three categories of TMS’s indicators. The other two are the development of Knowledge within the team and a development of knowledge of who knows what in the team (Meta-Knowledge). Each category of TMS’s indicators contains several indicators, listed in Figure 1. In a series of 3 studies (a total of 223 groups), I investigate the interrelationships between the indicators of TMS and their influence on group performance. In Study 1, I demonstrate that a common manipulation of TMS appears to affect only Credibility and Knowledge Stock; I discuss the implications. In Studies 2 and 3, I present results indicating that Coordination, Knowledge Stock, and Knowledge Differentiation (the extent to which members specialize in different areas) each have a positive relationship on group performance. The findings in this article suggest that TMS’s importance to group performance may be underestimated if only its Behavioral Indicators are assessed. Thus, future articles should consider the inclusion of measures of the Knowledge indicators of TMS–in addition to Behavioral Indicators–to measure TMS. (PsycINFO Database Record (c) 2019 APA, all rights reserved)