This article reports on a study that suggests ways that Writing Across the Curriculum/Writing in the Disciplines (WAC/WID) programs can increase the effectiveness of their efforts, including implementation of writingintensive courses, which are one of the Association of American Colleges and Universities' High-Impact Educational Practices. The study involved a collaboration between the Council of Writing Program Administrators (CWPA) and the National Survey of Student Engagement (NSSE) investigating the relationship between student writing and gains in learning and personal development. Twenty-seven questions focusing on writing were appended to the regular NSSE survey and administered at 80 bachelor's degree-granting institutions in the United States, yielding 29,634 surveys from first-year students and 41,802 surveys from seniors. Statistical analysis of the results identified three constructs relating to the way writing is assigned and used in coursework: Interactive Writing Processes, Meaning-Making Writing Tasks, and Clear Writing Expectations. More than the amount of writing students reported doing, these three highimpact writing practices were positively associated with several established constructs in the NSSE survey relating to students' participation in deep learning activities and to their personal and social development. Results of the study suggest important implications for how writing is integrated into coursework across the curriculum, what WAC and WID leaders can do to strengthen their cross-curricular implementation of writing, and how research can continue to explore the relationships between writing and learning in multiple settings.