Difficult temperament has been associated with fast weight gain and slow weight gain, although the latter mostly in referred subjects studies in late infancy. The current study set out to investigate early weight gain in relation to all domains of temperament in a community-screened sample. Weight gain from birth to 8 weeks was assessed in 75 infants recruited from local health care clinics who had demonstrated slow, average, or fast weight gain. Mothers completed a temperament questionnaire and a 2-day diary recording infant behaviors (sleeping, feeding, fussing, and crying). Weight gain from birth to 8 weeks was significantly related to infant temperament. The temperament dimension fear (acceptance or rejection of new objects or persons) was related to slow weight gain and the temperament dimension distress to limitations (negative emotionality and the infant's reaction to frustrating situations) was related to fast weight gain. The regression model explained 59% of the variance, with the temperament dimensions explaining 11%. Diary data showed that infants who scored high on fear tended to cry a lot, while infants with high scores on distress to limitations tended to sleep less and cry and fuss more. The results emphasize that different temperament domains influence slow and fast weight gain. In addition, the data suggest that infant temperament plays a part in physical development in early infancy.