This article addresses the ways in which learners' silence plays out within asynchronous and synchronous text-based, online communication. Our study takes an ethnographic perspective in examining how learners and instructors in two online courses use and interpret silence. The ways in which those learners and instructors eventually integrated silence into their online communication were interpreted as non-participation, confusion, marginalization, and thoughtful reflection. These findings have implications that are relevant to instructors' efforts to create constructive online learning environments and view silence as an important aspect of social presence. We thus propose the need for the development of a deeper analysis--both empirical and theoretical--on the notions of online silence, social presence, and communication.