Newborn infants with differential patterns of fetal growth, as determined by their weight-for-length, typically display behaviors which have been conceptualized as reflecting the integrity of the infant's behavioral organization. The newborn infant's sucking is one behavior that has been hypothesized to both reflect the effects of previous experiences on behavioral organization and affect the infant's future behavioral development. In particular, the infant's pattern of sucking activity may not only reflect the integrity of the infant's nervous system, it may also alter the temporal organization of the infant's behavioral state and motor activity by increasing behavioral quiescence. The purpose of this study was to compare the sucking activity of underweight-for-length (N = 30) and average-weight-for-length (N = 30) infants and its effects on behavioral state and motor activity. Fifteen low-PI and 15 average-PI infants were randomly assigned to each of two experimental conditions. / Master of Science