PIP: The determinants of weight and height are explored using nationally representative data for Kenya. The author also uses recall data on child birth weights to estimate conditional reduced-form demand relations for weight gain among 7907 children aged 0-5 years. Maternal education was found to be a significant determinant of weight, height, and weight gain, with secondary schooling having larger, but not significantly different effects than primary schooling. Per capita household expenditure is highly significant but with only small numerical effects. Birth weight has a large, negative effect upon subsequent weight gain, indicating almost complete catch-up growth by age one. The effect becomes more negative when birth weight is treated as an endogenous variable. There is no evidence of any catch-up growth beyond age three. The study results indicate that small deficits in birth weight are not likely to be permanent, with infants making up for birth weight deficits completely within the first year of life through biological catch-up growth.