There is growing recognition that learners in science need to become familiar with the discourse rules, rationale, claims, and procedures of traditional ways of representing scientific inquiry and findings. At the same time, some researchers in science education have claimed that students also need opportunities to write in ways that enable engagement, clarification, and consolidation of emerging understandings, where writing is used as a tool for shaping and clarifying knowledge. Each agenda has generated powerful new insights into the conditions under which, and the strategies whereby, student writing can support learning in science; but there is a need to clarify further the theoretical implications of this research, especially in the context of new technology-mediated, multi-modal learning environments. Drawing on this literature and other recent reviews, this paper identifies various implications in relation to the theory and practice of future student writing for learning in science.