Avoidance of adjacent consonants that are ‘sufficiently identical’ – that is, identical except for possible differences in a small subset of specific features – is argued to result from joint satisfaction of a constraint against geminates (identical adjacent consonants) and other active constraints that independently require assimilation with respect to those features ignored in the determination of identity. The crux of the proposal is the dependence of antigemination on independent assimilation processes, a prediction that is independently verified in case studies from English and Lithuanian. The factorial typology of constraints at the core of the proposal is demonstrated to closely fit a significant range of observed cases.