Dual display desktop computers are becoming more prevalent in the home, workplace, and schools, yet there has been little research into how learning and productivity are impacted by having a second display. One useful method in exploring this question is to measure cognitive load during an intensive learning event. This study compared perceived cognitive load among participants in a military training program using one or two computer displays. Participants using dual monitors reported lower unnecessary cognitive load than participants using one monitor. The implications of these findings for theory and practice are discussed.