Technical writing skills are widely considered to be critical for geologists and engineers. Iterative practice with technical writing throughout the undergraduate curriculum represents a common mode by which students develop their skills. The purpose of this study is to examine the efficacy of an iterative practice and feedback model in the context of a senior-level engineering geology class. Particular focus is paid to student performance improvement over the course of the semester and the factors that predict the efficacy of peer reviews in helping students to improve their reports. After validation of a report assessment rubric with students and TAs, students completed seven consulting-style technical reports covering seven different topics related to engineering geology. Quantitative data from rubric-based self- and peer assessments of draft reports and TA assessments of final reports were analyzed using regression to identify trends in technical writing performance. The increase in student writing performance beyond the first four reports was found to be limited. Students saw the greatest improvement in four specific rubric categories: transparency, completeness, style, and graphics. Although reviewer GPA was not found to be predictive of peer-review quality, reviewer performance on the assigned writing tasks was. Overall, this study finds that the iterative practice and feedback model is effective in promoting students' technical writing skills, and that the quality of peer reviews provided on report drafts influences student skill development.