The author argues that L2 fluency is not only a social product but also a mental process and much of that process contains learner responses to task design. Unfortunately, empirical research into the dynamic of how learner silence interacts with task design hardly exists to this day. In the literature on second language acquisition, it is talk, not silence, that receives recognition as output. However, to assume that output must always be audible represents a constricted way of understanding how learning progresses. Depending on how silence is employed, the occurrence of inner speech in the learner’s system deserves to be viewed as a type of production, especially when thoughts are taking shape in the mind. The chapter justifies the need to consider the role of silence in task design and task performance. Since the relationship between tasks and silence is under-explored, the author has conducted a series of research projects to uncover such dynamics. These studies are reported and discussed in detail, with concrete examples and pedagogical implications for materials development.