Subjects tried to halt an approaching or departing experimenter at a prespecified distance. In both the approaching and departing conditions, the subjects halted the mobile person at distances exceeding the preselected target distance, but the distance misestimation was greater for the approaching condition. This observation is inconsistent with current theories of personal space. This may be because most personal-space studies emphasize the inner boundary of personal space by investigating minimal acceptable distances or intrusions into personal space, whereas the phenomenon described here occurs at the outer boundary of personal space. Distance misestimation may lead to an alternative method of measuring personal space and emphasizes the necessity of investigating the phenomenological and subjective aspects of spatial behavior.