A new approach to modelling the individual human linear growth curve from birth to maturity is presented in detail. The model, which is also suitable for other measurements, breaks down growth mathematically into three additive and partly superimposed components--Infancy, Childhood and Puberty (the ICP-model). A key feature of this approach is that these components of the human growth curve from birth to adulthood strongly reflect the different hormonal phases of the growth process. As a result, the model provides an improved instrument for detecting and understanding growth failure. The model also sheds light on some central facets of human growth. For instance, the dramatic change in body proportions during the first years of life is found to be related to an enhanced influence of the Childhood component on the legs as compared with the trunk. The size of the Puberty component is shown to be time-invariant and to be superimposed on the decelerating Childhood component during adolescence. Early pubertal maturation is known to give a higher peak velocity than late maturation, so this variation in pubertal gain must be explained by the shape of the Childhood component alone.