The effect of the presence of a friendly animal on children's blood pressures and heart rates while resting and their cardiovascular responses to verbalization were examined. The presence of the dog resulted in lower blood pressures both while the children (N = 38) were resting and while they were reading. The effect of the presence of the dog was greater when the dog was present initially than when it was introduced in the second half of the experiment. We speculate that the animal causes the children to modify their perceptions of the experimental situation and the experimenter by making both less threatening and more friendly. This study provides insight into the use of pets as adjuncts in psychotherapy.