The problem of PhD attrition, especially at the dissertation-writing stage, is not solely related to mentoring, departments, or disciplines; it is a problem that affects the entire institution. As such, solutions require collaborative efforts for student success. Building on Yeatman's master--apprentice model, which assumes mastering disciplinary writing in singular advisor--student contexts, and Burnett's collaborative cohort model, which introduced doctoral dissertation supervision in a collaborative-learning environment with several faculty mentors in a single discipline, the Dissertation House model (DHM) introduces a model of doctoral dissertation supervision that involves multiple mentors across several disciplines. On the basis of more than 200 students' reflections, we find that challenges in completing the dissertation extend beyond departmental and disciplinary boundaries. The DHM's multidisciplinary approach preserves the traditional master--apprentice relationship between faculty and students within academic departments while providing an additional support mechanism through interdisciplinary collaborative cohorts. Using Thoits's coping assistance theory and data from DH students over a 10-year period, the DHM incorporates Hoadley's concept of knowledge communities to establish a successful dissertation-writing intervention for graduate students across doctoral programs. Using propensity score analysis, we provide in this study an empirical assessment of the benefits and efficacy of the DHM.