The current study examined how assessments of copresence in an immersive virtual environment are influenced by variations in how much an embodied agent resembles a human being in appearance and behavior. We measured the extent to which virtual representations were both perceived and treated as if they were human via self-report, behavioral, and cognitive dependent measures. Distinctive patterns of findings emerged with respect to the behavior and appearance of embodied agents depending on the definition and operationalization of copresence. Independent and interactive effects for appearance and behavior were found suggesting that assessing the impact of behavioral realism on copresence without taking into account the appearance of the embodied agent (and vice versa) can lead to misleading conclusions. Consistent with the results of previous research, copresence was lowest when there was a large mismatch between the appearance and behavioral realism of an embodied agent.