Abstract. Motivated by applications to graph morphing, we consider the following compatible connectivity-augmentation problem: We are given a labelled n-vertex planar graph, G, that has r ≥ 2 connected components, and k ≥ 2 isomorphic planar straight-line drawings, G 1 , . . . , G k , of G. We wish to augment G by adding vertices and edges to make it connected in such a way that these vertices and edges can be added to G 1 , . . . , G k as points and straight-line segments, respectively, to obtain k planar straight-line drawings isomorphic to the augmentation of G. We show that adding Θ(nr 1−1/k ) edges and vertices to G is always sufficient and sometimes necessary to achieve this goal. The upper bound holds for all r ∈ {2, . . . , n} and k ≥ 2 and is achievable by an algorithm whose running time is O(nr 1−1/k ) for k = O(1) and whose running time is O(kn 2 ) for general values of k. The lower bound holds for all r ∈ {2, . . . , n/4} and