This interpretive study of two fifth-grade students' intrinsic motivation for writing examines the ways in which children who self-sponsor writing express “flow” experiences associated with writing. Considering a sense of flow seems to address why some children persevere when faced with challenging tasks and why they spend so much time and effort engaged in activities they find interesting. In addition to the challenge of writing, the social context of the classroom influenced opportunities for student-controlled writing. Flow experiences described by the boys occurred when each controlled important aspects of writing, such as ownership, genre, style, and length—although the social context of the two classrooms varied widely. The boys featured in this report demonstrated that elementary students identified as avid writers can differentiate between flow experiences and nonflow experiences associated with writing, and they describe flow experiences in terms similar to those reported in studies on adolescents and adults.