This chapter explores how writing can support the development of critical thinking skills. Writing-to-think aims to develop unformed early thoughts, spark possible lines of inquiry, and test out ideas. Writing is so effective in contributing to thinking because it is hard to do, because it requires you to express your thoughts with coherence and clarity, and because it allows you space and freedom to try out your voice. When writing-to-think, you must adopt two different personas: the writer and the critic, and never try to be both at the same time. The chapter also differentiates between free writing and direct writing. The two main obstacles to writing-to-think are confidence and time. Writing-to-reflect can be used to uncover and overcome obstacles you are facing in relation to this or other tools.