A significant body of research identifies a large number of team composition characteristics that affect the success of individuals and teams in cooperative learning and project-based team environments. Controlling these factors when assigning students to teams should result in improved learning experiences. However, it is very difficult for instructors to consider more than a few criteria when assigning teams, particularly in large classes. As a result, most instructors allow students to self-select teams, randomly assign teams, or, at best, balance teams on a very limited number of criteria. This paper describes the design of "Team-Maker," a web-based software tool that surveys students about criteria that instructors want to use when creating teams and uses a max-min heuristic to determine team assignments based on distribution criteria specified by the instructor. The "Team-Maker" system was validated by comparing the team assignments generated by the "Team-Maker" software to assignments made by experienced faculty members using the same criteria. This validation experiment showed that "Team-Maker" consistently met the specified criteria more closely than the faculty members. We suggest that "Team-Maker" can be used in combination with the "Comprehensive Assessment of Team-Member Effectiveness" ("CATME") peer evaluation instrument to form a powerful faculty support system for team-based and cooperative learning and for a variety of research purposes. Internet access to both the "Team-Maker" and "CATME" systems is freely available to college faculty in all disciplines by selecting the "request faculty account" button at https://www.catme.org.