This study examines the impact of course-based collaboration between an elementary teacher education program and a writing center. Written texts of preservice teachers (n=141) were analyzed to establish the most frequent errors/problems in their writing. Based on the first analysis, the researchers designed and implemented an intervention focused on language usage, content, and coherence. The intervention group (n=41) significantly outperformed the control group (n=41) after a single intervention session, with large effect sizes for language usage and content, and a medium to large effect size for coherence.