We study the problem of computing evolutionary orderings of families of sets, as introduced by Little and Campbell [1]. Definition 1. Let S be a family of subsets of some universe U . We say that S is evolutionary if there exists an ordering of its sets S = {S 1 , S 2 , . . . , S m } such that:• Each set brings a new element, i.e. S i i−1 j=1 S j• Each set, except the first one, has an old element, i.e. S i ∩ i−1 j=1 S j = ∅ The associated algorithmic problem is the following: Evolutionary Ordering Input: A family of subsets S of some universe U . Question: Is S evolutionary?We determine the computational complexity of this problem.Theorem 1. Evolutionary Ordering is NP-hard.