In this chapter, we focus on heuristics for network design problems. Network design problems have many important applications and have been studied in the operations research literature for almost 40 years. Our goal here is to present useful guidelines for the design of intelligent heuristic search methods for this class of problems. Simple heuristics, local search, simulated annealing, GRASP, tabu search, and genetic algorithms are all discussed. We demonstrate the effective application of heuristic search techniques, and in particular genetic algorithms, to four specific network design problems. In addition, we present a selected annotated bibliography of recent applications of heuristic search to network design.