The growth of a random sample of coloured children in Cape Town was studied from birth until 5 years. At birth they were relatively light and short for gestational age. Size at birth correlated with social class. A rapid postnatal weight gain rendered them relatively overweight between 3 and 6 months. Thereafter they became lighter and shorter than the NCHS reference values and this persisted throughout the preschool period. Genetic factors, reflected by parental growth, were found to predict growth during childhood, but they were more predictive of weight and head circumference than of length. From 12 months onwards, socio-economic factors played a significant role in determining growth even after the effects of the genetic factors had been taken into account.