Computing optimal strategies to commit to in general normal-form or Bayesian games is a topic that has recently been gaining attention, in part due to the application of such algorithms in various security and law enforcement scenarios. In this paper, we extend this line of work to the more general case of commitment in extensiveform games. We show that in some cases, the optimal strategy can be computed in polynomial time; in others, computing it is NPhard. Categories and Subject Descriptors I.2.11 [Distributed Artificial Intelligence]: Multiagent Systems; J.4 [Social and Behavioral Sciences]: Economics; K.4.4 [Computers and Society]: Electronic Commerce General Terms Algorithms, Economics, Theory Keywords noncooperative game theory, commitment, Stackelberg, extensiveform games