Data on the relationships between individual body size, age and reproduction were obtained for a sample of Smooth newts collected from several sites in southern England. Age was determined by counting lines of arrested growth in histological sections of humerus. In males and females, body size increases with age, but only in the former sex is the correlation statistically significant. In both sexes, there is great inter-individual variability in body size within a year class. Measures of fecundity (testis size, ovary size, clutch size and oocyte size) are positively correlated with body size, but not age. The timing of first reproduction does not seem to depend on the attainment of a fixed body size; the earliest age at first reproduction is two or three years. Together with information obtained during previous studies, the data we present support the hypothesis that the Smooth newt may be an r-selected, colonizing species.