Associations were sought between somatic measures and developmental status at 4 years among groups of children who had been small-for-dates (SFD), average-for-dates (AFD) and large-for-dates (LFD) at birth. When the three groups were combined, and adjustment made for sex, social class and series, a significant correlation was found between head circumference and total scores. Within the SFD and AFD groups no correlations were found between any somatic measures and aspects of development; and the only significant finding in the LFD group was a negative correlation between weight-for-height and total developmental scores. The somatic measures were then divided into three subgroups comprising children who had small, average, and large values for that measure, and developmental scores for each subgroup were computed. Within all three birthweight groups significant differences were found for head circumference: those with relatively small heads having lower scores than the rest.