This mixed method investigation included a quasi-experiment examining if revision instruction enhanced the substantive revising behavior of 15 English language learner (ELL) and multilingual 10th grade students enrolled in an English class for underperforming students in comparison to 14 non-ELL and multilingual students from the same class who did not receive such instruction. The study also involved a qualitative analyses of the revisions made by students from both groups to more fully describe the type and frequency of substantive revisions made. In terms of the quasi-experiment, students in the treatment group made more Developing Argument revisions than the control group. The qualitative analysis revealed the specific moves students made in their revision work to develop argument including: utilizing text, personal opinion, interpreting text, extending argument, and asking a question. Theoretical and educational implications of the findings are discussed.