The U.S. Army recently fielded a dismounted infantry simulator to train small-unit tactical skills and to link small-unit simulation training with armored vehicle simulation. The Dismounted Soldier Training System (DSTS) uses a helmet-mounted display and controllers mounted to the surrogate weapon to allow Soldiers to interact with the virtual environment. Creating effective simulation for dismounted infantry is difficult because replicating the sensory-motor affordances for physical orientation and situational awareness and maintaining inter-personal communication are technically complex but essential to execution of small-unit tactical skills. In order to determine the extent to which DSTS trainability was impacted by sensory-motor orientation and communication issues, Soldier performance data was collected during two large-scale capabilities experiments. In both experiments, Soldiers conducted infantry small-unit tasks in DSTS and provided feedback on the similarity and difficulty of performing individual skills (e.g., walk/run, know location of others, and communicate with others). In particular, DSTS capabilities to provide visual identification, auditory localization (including communication), and interaction with the environment were analyzed. For comparison purposes, data from a motion-capture-simulation system was also collected during one of the experiments. The potential advantages of motion-capture systems hinge on the use of natural locomotion to translate interaction in the virtual environment. The results indicated that DSTS visual identification capabilities were mostly similar to but somewhat more difficult than live performance. However, auditory localization and interaction with environment capabilities were dissimilar to and more difficult than live performance. The motion-capture system results were consistent with the DSTS results except on ratings for movement capabilities. Taken together, the results suggested that current dismounted-infantry simulation technologies do not fully provide the basic sensory-motor orientation and communication capabilities that are critical for dismounted simulation trainability. The results also identified specific simulation capabilities that must be addressed in order to produce effective dismounted-infantry simulation.