The law of contagion is one of the laws of sympathetic magic put forth about 100 years ago to account for magical belief systems in traditional cultures. This law holds that when two objects (usually animate) come into contact with each other, there is a potentially permanent exchange of properties between them. In a prior study, we demonstrated that this law fits well with a variety of behaviors of Americans in response to disgusting and dangerous objects, primarily in the food domain. In the present study, we explored by questionnaire the operation of this principle in the interpersonal domain. We examined two dimensions of contagion. First, we show that the history of human contacts with an object can affect the value of that object both positively and negatively, depending on the nature of one’s relation to its contact source. Second, we report results consistent with a belief in both “forward” action (in which influence passes from source to recipient) and “backward” action (whereby acting on a person’s possessions or bodily residues can influence that individual). We conclude that contagion is an operative belief in American culture.