An experiment was conducted to test the theory that young boys prefer the companionship of their fathers in play activities to that of their mothers, while young girls have no particular preference. It was hypothesized that a boy has this preference because he has been cared for primarily by his mother, and his discovery of sex-identity leaves him particularly insecure in his shifting sex-role, thus producing a strong affinity for the most available masculinity model, his father. Girls develop no such preference because they have been primarily cared for by the same-sex parent, a less confusing and less traumatic situation. This theory was tested by placing children in seven play situations and asking them which parent they would like to have join them in each of the activities. The subjects were 150 2-, 3-, and 4-year-olds (76 boys and 74 girls). The criterion for parent preference was 4 or more choices of one parent. Analysis of the data revealed that the boys significantly preferred the father to the mother. Girls showed no consistent parent preference for the total sample, but this was the result of significant preferences: for the father at age 2 and for the mother at age 4. (MH)