This paper examines implications for morpho-phonology of a model that minimizes the role of an innate linguistic endowment in grammar formation. ‘Bottom-up’ learning results in mental representations that form sets from perceived morphs but do not involve abstract ‘underlying’ representations. For production, syn- tactic/semantic features (S-features) identify morphs to be com- piled into words. When multiple morphs bear the same S-feature, the grammar must select among the possible contenders. Selection involves phonological regularities or sub-regularities and morpho- phonological as well as idiosyncratic choice; when all else fails the default morph is selected. The model unifies the formal character- ization of suppletion, sub-regularit...