The capacity to write well is fundamental to academic success and productive participation in civic life. And yet, despite the evident power of writing, our understanding of being a writer and the teaching of writing lags behind our understanding of the teaching of reading. In this chapter, we provide an introductory overview of research on writing, including the different ways writing has been conceptualised; what we know about becoming a writer, and about development in writing across the years of schooling; and empirical evidence about effective pedagogies to support the development. The chapter offers an interdisciplinary understanding of writing development, conceiving of it as a dynamic and multidimensional concept. This integrated understanding places writers’ metalinguistic understanding, and their growing sense of audience and self at the centre of the writing process. As such writers’ linguistic development and mastery of genre forms are mediated through their perception of themselves and others, and the authority they invest in learning and writing.