The present study examined infants' reactions to separation from and reunion with their mothers, and attempted to determine if these behaviors were related to the infants' experiences with their mothers at home. The subjects, 60 Caucasian mother-infant pairs, were observed at home two hours on each of two days and in a laboratory setting. The infants, first-born 10-month-old girls, were half from middle class families and half from working class families. There were no social class differences in the frequency of crying upon separation. Infants of working class mothers who worked could better tolerate brief separations from their mothers than children of non-working mothers of the same class. Also examined was the influence of experiences at home on the various laboratory measurements. Two-way analyses of variance revealed that middle class infants who cried and/or crawled upon separation from mother spent more time face-to-face with their mothers at home, while working class infants who cried and/or crawled spent less time in this position. (Author/AJ)