Mothers of preterm and full term infants completed Abidin's Parenting Stress Index at 8 months, Waters' Attachment Behavior Q-sort at 12 months, and Bates' Infant Characteristics Questionnaire at 18 months. These instruments provided assessments of fussy and difficult infant behaviors that were moderately stable over the 10 months (r's> .48). On the basis of home observations at 12 months, the infant-mother relationships were classified as secure, avoidant and ambivalent. Cassidy has proposed that infants in ambivalent relationships may have poor affect regulation. Consistent with Cassidy's view, mothers in ambivalent relationships reported more fussy and difficult infant behavior at each age than did mothers in secure or avoidant relationships. Mothers of preterm infants reported higher scores on the Child Domain of the Parenting Stress Index than mothers of full term infants. The birth groups did not differ on the 12- and 18-month assessments.