Indices of social mastery motivation in Down syndrome (DS) and nondelayed infants, matched on Bayley mental scores, were observed during social tasks that encouraged socially motivated behaviors and object-play tasks that did not encourage these behaviors. During the object play, the DS infants' object-directed behaviors were not appreciably lower than the nondelayed infants', while their social behaviors were significantly lower. During social tasks, no significant difference was found. The nondelayed infants' positive affect was related to social and cognitive competence, but for the DS infants, only to social competence. The findings suggest differences in behavioral integration between the two samples.