The article presents the results of a randomized experimental study of a writing curriculum for college developmental writing courses based on strategy instruction with self-regulation integrated with practices common in college composition. Students in a full semester course learned strategies for planning and revising based on rhetorical analysis and genres. In addition, they learned metacognitive, self-regulation strategies for goal setting, task management, self-evaluation, and reflection. A prior quasi-experiment found positive effects of the curriculum on writing quality, self-efficacy, and mastery motivation. The current study included 19 instructors and 207 students across two colleges. Using hierarchical linear modeling (HLM) with students nested within instructors and with condition and college as factors and pretest scores as covariates, analyses found positive effects of the treatment for quality of argumentative writing (ES = 1.18), quality of writing on an independent writing assessment (ES = 0.67), and several motivation outcomes, including self-efficacy (for tasks and processes, ES = 0.50; for grammar, ES = 0.36; and for self-regulation, ES = 0.40), affect (ES = 0.32), and beliefs about the importance of content (ES = 0.29). No significant effects were found for grammar/conventions or reading comprehension. Teachers in the treatment condition commented positively on the approach and noted improvements in student writing and motivation. Students also shared positive experiences and noted improvement in their writing. [For the corresponding grantee submission, see ED614889.]