Controversies, i.e., multiple theory confrontations, may have a strong impact on the development of science. By an analysis of the so-called resonance controversy in chemistry the view that controversies and their resolution differ considerably from the process of theory succession is defended. It is argued that controversies are symptomatic of foundational problems, produce theory-scattering or domain-splitting, and induce ontological shifts. An explication is given of the role of existence claims and the applicability of Ockham's Razor in the resolution of controversies. (...) The requirement of a realistic interpretation of theories at all times, as defended by some philosophers, is criticised. (shrink)