This study evaluated the utility of generic teamwork skills training for enhancing the effectiveness of action teams. Results from 65 four-person action teams working on an interdependent command and control simulator revealed that generic teamwork skills training had a significant and positive impact on both cognitive and skill-based outcomes. Trained team members evidenced higher levels of declarative knowledge regarding teamwork competencies and demonstrated greater proficiency in the areas of planning and task coordination, collaborative problem solving, and communication. Furthermore, results indicated that cognitive and skill based outcomes were interrelated. Team members' declarative knowledge regarding teamwork competencies positively affected planning and task coordination, collaborative problem solving, and communication skills. However, we found that the effects of declarative knowledge differed across team members depending on their roles and responsibilities. The team benefited the most from the knowledge held by the team member who occupied the most critical position in the workflow. Implications of these findings for future research and practice are discussed.