Program dependence information is useful for a variety of software testing and maintenance tasks. Properly defined, control and data dependencies can be used to identify semantic dependencies. To function effectively on whole programs, tools that utilize dependence information require information about interprocedural dependencies: dependencies that exist because of interactions among procedures. Many techniques for computing data and control dependencies exist; however, in our search of the literature we find only one attempt to define and compute interprocedural control dependencies. Unfortunately, that approach can omit important control dependencies, and incorrectly identifies control dependencies for a large class of programs. This paper presents a definition of interprocedural control dependence that supports the relationship of control and data dependence to semantic dependence, an efficient algorithm for calculating interprocedural control dependencies, and empirical results obtained by our implementation of the algorithm.