Repeated impact of foreign bodies on laminated composites may give rise to delamination damage. In this paper, experimental information is employed to formulate a growth law for delamination damage in terms of the impact energy per impact and number of impacts. The growth of regions of delamination is considered a stochastic problem, and hence the growth law is placed in a probabilistic setting by considering the evolution of a probability density function of delamination damage as the number of impacts increases. For a specific number of impacts, this formulation is used to determine the probability of a delamination in a selected range of delamination sizes. The formulation has been extended to include the effect of probability of detection as well as the effect of variable impact energy according to a probability density function. Finally, random variation of impact location is taken into account by the equivalent effect of a discrete probability function for the number of impacts at a fixed location.