Conversational grounding theory proposes that language use is a form of rational joint action, by which dialog participants systematically and collaboratively add to their common ground of shared knowledge and beliefs. Following recent work applying game theory to pragmatics, this thesis develops a game-theoretic model of grounding that formalizes the core claims of grounding theory. This game-theoretic model is based on the concept of signaling games, originally proposed as a model of linguistic convention. In order to account for grounding, this thesis proposes to extend signaling games with an observation model, which allows for the possibility that the actions a participant takes may only be partially observable to others. This game-theoretic model is applied to the domain of referential communication tasks, a type of task commonly used in psycholinguistic experiments. The model generates predictions about how dialog participants in such tasks package referential expressions into installments, by calculating an optimal trade-off of cost and uncertainty. These predictions are experimentally evaluated with a novel variant of an online referential communication task.