People make comprehension easier by predicting upcoming language. We might therefore expect prediction to occur during the extremely difficult task of simultaneous interpreting. This paper examines the theoretical and empirical foundations of this premise. It reviews accounts of prediction during comprehension in both monolinguals and bilinguals, and discusses these theories in light of experimental data (e.g., using the visual-world paradigm). It considers how these accounts may be applied to the unique and ecologically valid context of simultaneous interpreting, when two languages are used concurrently, one overtly engaging the comprehension system, and the other overtly engaging the production system. It then posits a role for the production system in prediction during comprehension and develops a theoretical framework for prediction-by-production in simultaneous interpreting that has implications for our understanding of prediction during language comprehension.