This chapter discusses the affective domain of motivation, which is associated with goal theory, self-determination, engaging instruction, value theory, writer attitude, and interest theory. Motivation is a vital force in increasing writers’ engagement and their writing performance. Evidence is presented about the strong relationship between writer motivation and academic achievement. Theory, research, and educational practices associated with developing children’s motivation in writing and its important role in developing confident and effective writers are also explored in the chapter. This includes discussion on the typical behaviours witnessed in a rich variety of educational research and differences observed in the behaviour of pupil-writers who hold high and low levels of motivation. Finally, the authors share the relationship between developing apprentice writers’ intrinsic, extrinsic, and situational motivation and the 14 principles of effective writing teaching. They give examples of the kinds of instructional practice carried out by the most effective teachers of writing.