We propose composition languages as a way to specify actor-oriented models, or hierarchical networks of concurrent components which communicate with one another through ports. The key to composition languages is the ability to succinctly specify higher-order models. As an example, a higher-order model may be a distributed sort model. The model may be parameterized by a divide component (or model), a conquer component, and the respective numbers of divide and conquer components. A programmer will specify this higher-order model once and can then use it for an arbitrary number of components with arbitrary divide and conquer components. We believe composition languages will become increasingly important in actor-oriented design, since they will enable rapid development of large systems.