Writing is complex, and the more researchers understand the cognitive processes and engagement for writing, the more complex the relationships between cognition and producing writing appear. Writing theory is constantly shifting from a focus on mechanics and form to a focus on creativity and sociability. This literature review analyzes four leading theories for writing instruction: the cognitive processes theory, the sociocultural theory, social cognitive theory, and ecological theory. To demonstrate how these theories develop into practice, strategies supporting each theory and classroom examples are provided.