Mothers and Fathers, Girls and Boys: Attachment Behavior in the First Two Years of Life1

ABSTRACT Twenty children, 10 boys and 10 girls, were seen at one and two years of age in a free play situation. At each age each infant first played with one parent and then a week later with the other. Attachment behavior (proximal and distal modes) was observed and found to be affected by the sex of infant and sex of parent. Moreover, Bayley Mental Maturity Index obtained at two years was found to be correlated with certain patterns of attachment behavior over the first two years of life. These findings are discussed in terms of attachment theory and the etiology of sex differences in interpersonal relations.