This paper argues that conceptualizing unity as "interconnection" (rather than reduction) provides a more fruitful and versatile framework for the philosophical study of scientific unification. Building on the work of Darden and Maull, Kitcher, and Kincaid, I treat unity as a relationship between fields: two fields become more integrated as the number and/or significance of interfield connections grow. Even when reduction fails, two theories or fields can be unified (integrated) in significant ways. I highlight two largely independent dimensions of unification. (...) Fields are theoretically unified to the extent that we understand how the ontologies, concepts, and generalizations of these fields are connected. (Reductionism is one form of theoretical unity, but not the only form). Fields are practically unified through heuristic connections (e.g., using the heuristics of one field to generate hypotheses in another field) and by the development of methods for integrating the qualitatively distinct bodies of data generated by the two fields. I discuss the relationship between paleontological and neontological systematics to illustrate the utility of conceptualizing unity as interconnection. (shrink)