This study reports findings from a multisite cluster randomized controlled trial designed to validate and scale up an existing successful professional development program that uses a cognitive strategies approach to text-based analytical writing called Pathway to Academic Success. Multilevel models revealed significant effects on a holistic measure of an on-demand writing assessment (d = .32) as well as on 4 analytic attributes: content (d = .31), structure (d = .29), fluency (d = .27), and conventions (d = .32).