This study investigated the role of dynamic written corrective feedback (DWCF; Evans, Hartshorn, McCollum, & Wolfersberger, 2010; Hartshorn & Evans, 2015; Hartshorn et al., 2010), a mode of providing specific, targeted, and individualized grammar feedback in developmental English as a second language (ESL) writing classes (pre-first year composition) at a large western U.S. research university. Via a quasi-experimental design investigating DWCF at three different levels of developmental ESL writing classes across three terms with 325 student participants, results of this study suggest that multilingual students become better at self-editing and have more accurate timed writing paragraphs after taking classes that supplement grammar instruction using DWCF than those who take classes with only traditional grammar instruction. Specific error categories were investigated (global, local, and mechanical, per Bates, Lane, & Lange, 1993), with largely significant results across all error types at each language level, indicating that DWCF may be an effective pedagogical intervention to improve linguistic accuracy.