Infant feeding guidelines recommend exclusive breast-feeding to the age of 6 months; complementary foods should not be introduced before this age. This study examined parent and infant psychosocial determinants of the early introduction of complementary foods. Analyses were conducted on a representative sample of children born in Québec (Canada) in 1998 (n = 2,223), surveyed through the Québec Longitudinal Study of Child Development. Of the children, 61% received complementary foods prior to the age of 4 months. A multiple logistic regression analysis revealed the early introduction of complementary foods was more likely when mothers were younger, less educated, of lower socioeconomic class, and when they felt they had little influence on their child's development. Higher parental confidence in caring for the infant was also associated with the early introduction of complementary foods (p < or = .05). Future research must carefully consider the psychosocial aspects involved in adhering to infant feeding guidelines.