This paper deals with the problem of finding a base and strong generating set for the group generated by a given set of permutations. The concepts of base and strong generating set were introduced by Sims [5], [6] and provide the most effective tool for computing with permutation groups of high degree. One algorithm, originally proposed by Sims [7], is described in detail; its behavior on a number of groups is studied, and the influence of certain parameters on its performance is investigated. Another algorithm, developed by the author, is given, and it is shown how the two algorithms may be combined to yield an exceptionally fast and effective method.