In cognitive networks, cognitive (unlicensed) users need to continuously monitor spectrum to detect the presence of primary (licensed) users. In part I, we have illustrated the benefits of cooperation in cognitive radio by considering a simple two-user network and showing improvement in agility. In part II, we investigate multiple cognitive user networks. We first consider multiuser single carrier networks and develop sufficient conditions for agility gain when the cognitive population is arbitrarily large. We then propose a practical algorithm which allows cooperation between cognitive users in random networks. Finally, we provide an example to illustrate the concepts developed in this paper.