Joint Terminal Attack Controllers (JTACs) sometimes have to rely on trained Joint Fires Observers (JFOs) during combat to provide them with timely and accurate targeting information in support of close air support operations. Simulator-based training capabilities are available to most JTACs and JFOs but they do not often train together in such environments. Therefore, a key question is the extent to which simulation-based training (SBT) can enhance the operational effectiveness of JTAC/JFO teams. Our research addresses this question by developing a first-ever JTAC/JFO integration study to examine the effectiveness of integrated training via multiple objective and subjective measures. Because this was the first study of its kind, we conducted a preliminary evaluation as an initial step to explore the possibility of effectively training JTACs and JFOs together in a simulation-based environment. Sixteen Air Force JTACs and five Army JFO personnel participated in week-long team training research trials. Training was conducted via the Joint Terminal Attack Controller Training Rehearsal System simulator (JTAC-TRS) to provide simulated scenario training experiences. Objective measures of performance were collected throughout the training week via the Performance Evaluation Tracking System. Subjective measures of mission effectiveness were collected via observation and evaluation by researchers and JTAC instructors. JTAC/JFO teams rely heavily on verbal communication and coordination to accomplish mission objectives. Therefore, this study also tested innovative methods for measuring team effectiveness reflecting these unique communication and coordination activities. As expected, results from this study found that JTAC/JFO team performance improved significantly from pre- to post-training. More importantly, JTAC and JFO participants reported that this training was both valuable and necessary. This suggests that training in a simulation-based environment for JTAC and JFO personnel at the team level can significantly enhance training outcomes, including learning, performance, and overall mission effectiveness or transfer.