WEBER, RUTH A.; LEVITT, MARY J.; and CLARK, M. CHERIE. Individual Variation in Attachment Security and Strange Situation Behavior: The Role of Maternal and Infant Temperament. CHILD DEVELOPMENT, 1986, 57, 56-65. Theories of temperament suggest that both maternal and infant temperament might affect a child's mode of interacting not only with the mother but also with unfamiliar adults. 36 mother-infant dyads were videotaped in the Ainsworth Strange Situation when the infants were 13 months old. These tapes were scored for crying intensity and duration, interactive behavior, and attachment classifications. Lerner's Dimensions of Temperament Survey was completed by the mothers for themselves and for their infants. Mothers of attachment Type A infants scored significantly higher on intensity of reaction than did mothers of Type B and C infants, and mothers of Type B3 and C infants scored lower on adaptability to new situations than did mothers of either A or B1 and B2 infants. Maternal adaptability was also a significant predictor of infant crying, suggesting that the mother's own hesitancy in novel situations is transmitted to the infant. Infant temperament, particularly adaptability, was related to the infant's behavior toward the stranger. A summary rating of infant difficulty was correlated with resistance to both the mother and the stranger. The results suggest that various aspects of Strange Situation behavior are related to both maternal and infant temperament, and that maternal temperament is a predictor of attachment security, particularly for Type A mother-avoidant infants.