Indiana University-Purdue University Indianapolis (IUPUI) / As organizations use more and more work teams, selecting and assembling effective teams is becoming increasingly important. Past research and theory has demonstrated that informal roles serve as a critical linking mechanism between individual-level characteristics such as personality and team-level effectiveness. The present study builds upon this area of research and theory by testing the individual-level link between personality and informal roles and the team-level link between team informal role configuration and team effectiveness. These links were tested using a sample of 152 undergraduate students participating in 38 teams of four. The teams engaged in an information-sharing business simulation where the goal was to generate the highest possible profits across two simulated business years. At the individual level, the Big Five personality dimension Agreeableness positively and significantly correlated with the adoption of the Communicator role, while the relationship between Conscientiousness and the Contractor role approached significance. With regard to the team level, a positive relationship was found between the number of Completer roles performed within a team and the level of team effectiveness for the first simulated business year, and the relationship between the total number of informal roles performed within a team and team effectiveness in the first simulated year was found to be marginally significant. Using a criterion profile analysis approach, two criterion patterns were identified in which optimal informal role configuration patterns yielded high levels of team effectiveness. Overall, results from this study lend some support to the demonstrated links between personality and informal roles and informal role configuration and team effectiveness, which have important implications for organizational selection and employee development.