TeenACE for Science (TAS) is a writing intervention that combines components of Multimedia Technology, Universal Design for Learning (UDL), and Self-Regulated Strategy Development (SRSD) to help students develop expository writing skills in science. This developmental study examined the effect of the TAS intervention with two groups of culturally and linguistically diverse middle school students. Forty-six students in two classrooms that included general and special education students participated in a 12-week intervention during which they wrote multiple science reports. Students used the multimodal features of a productivity software (PowerPoint) to organize pictures and headings, take notes on a cognitive map, type in text, and record their voices narrating what they had written. This mixed methods study utilized pre-post tests and curriculum-based measures to examine quantitative changes. Qualitative measures included surveys and focus groups. Pre-post test results showed that students scored significantly higher on two Woodcock Johnson III subtests (Writing Fluency and Writing Samples) though no significant change was noted on the Editing subtest. Teachers rated the intervention as relevant, useful, and high quality; they reported continued use of the same protocol at a 1-year follow-up.