Cooperative communication has received tremendous interest for wireless networks. Most existing works on cooperative communications are focused on link level physical layer issues. Thusly, the impacts of cooperative communications on network level upper layer issues, for example, topology control, routing, and network capacity, are largely ignored. In this article, we propose a Capacity-Optimized Cooperative (COCO) topology control scheme to enhance the system limit in MANETs by jointly considering both upper layers network capacity and physical layer cooperative communications. Through simulations, we demonstrate that physical layer cooperative communications impacts on the network limit, and the proposed topology control plan can sustainably enhance the network capacity in MANETs with cooperative communications.