A fully connected network topology is critical to many fundamental operations in wireless ad hoc networks. We study the problem of deploying additional wireless nodes to improve the connectivity of an existing wireless network. Given a disconnected network, we consider the Connectivity Improvement (CI) problem, i.e., how to deploy as few additional nodes as possible so that the augmented network is connected. We first prove the NP-completeness of CI, and then present a Delaunay Triangulation-based algorithm, Connectivity Improvement using Delaunay Triangulation (CIDT). We discuss several variations of CIDT, and propose two additional optimization techniques to further improve the performance. Finally, we demonstrate the effectiveness of CIDT, and compare the performance of its variations via J-Sim simulation.