Recent yearly bole growth of individual trees, as estimated from height and annual growth ring measurements, is considered as a function of the number, distance and size of neighbours in a young Pinus rigida stand in New Jersey. Results are consistent with a model in which the growth of an individual is inversely related to the total effect of interference, and the contribution of each neighbour to this effect is additive in proportion to its size and inversely proportional to the square of its distance. While results show, as expected, that the effect of a neighbour decreases with its distance, they do not allow one to distinguish between alternative formulations with confidence, but a modified version of the model in which the effect of a neighbour decreases with its distance always resulted in a slightly improved fit over the original formulation in which a neighbour's effect decreases with the square of its distance. -from Author