Three-dimensional synthetic worlds introduce possibilities for nonverbal communication in computer-mediated language learning. This paper presents an original methodological framework for the study of multimodal communication in such worlds. It offers a classification of verbal and nonverbal communication acts in the synthetic world "Second Life" and outlines relationships between the different types of acts that are built into the environment. The paper highlights some of the differences between the synthetic world's communication modes and those of face-to-face communication and exemplifies the interest of these for communication within a pedagogical context.