Abstract. We study the “subgraph connectivity” problem for undirected graphs with sublinear vertex update time. In this problem, we can make vertices active or inactive in a graph G, and answer the connectivity between two vertices in the subgraph of G induced by the active vertices. In this paper, we solve two open problems in subgraph connectivity. We give the first subgraph connectivity structure with worst-case sublinear time bounds for both updates and queries. Our worst-case subgraph connectivity structure supports ˜O(m4/5 ) update time, ˜O(m1/5 ) query time and occupies ˜O(m) space, where m is the number of edges in the whole graph G. In the second part of our paper, we describe another dynamic subgraph connectivity structure with amortized ˜O(m2/3 ) update time, ˜O(m1/3 ) query time and linear space, which improves the structure introduced by [Chan, Pˇatra¸scu, Roditty, FOCS’08] that takes ˜O(m4/3 ) space.