Reflections on crossing disciplinary lines abound in the scientific community. Can cross-disciplinary approaches, with all their complexity and particularities, provide the way forward in the search for practical solutions to real-world problems? In this article, the author addresses how the debate on cross-disciplinarization pertains to the field of policy evaluation. Evaluation is appropriate terrain for such a discussion as this particular field of social science seeks to produce useful knowledge for both managers and policy makers. As such, the author offers a general account of the advantages and disadvantages of cross-disciplinary evaluation. Because evaluation requires close collaboration between individuals from different domains and backgrounds, the author further outlines the specific challenges that face the practitioner when conducting a cross-disciplinary evaluation. (Contains 2 notes.)