This study formulated a multivariate model of early infant competence from variables representing a transactional perspective of developing competence in early infancy. The measures used in the competence model were: birth weight; habituation index; personality ratings of the infants' social orientation and task orientation; ratings of maternal responsiveness to infant distress and social signals; and measures of observed maternal latency of response to infant distress and vocal signals taken in the home. The sample consisted of 51 middle income white families with first born infants of normal birth weight and free of significant birth defects. The model was validated against the Bayley Scales of Mental and Motor Development, when the infants were 2 1/2 and 6 months old, using multiple linear regression analysis. Results are presented for infant and maternal variables which were found to be predictive of mental and motor development at 2 1/2 and at 6 months. Sex differences in patterns of results across time are also presented and discussed. It was concluded that the acquisition of early competence appears to involve the interplay of maturational, personality, and environmental events and that the infant's own characteristics appear to weigh heavily in his/her transactions with the environment in early infancy. (Author/JMB)