In this talk, I argue that affix order in Washo is partially phonologically conditioned. Non-transitivity and semantic opacity in Washo affix order are caused by a stem-level violation of affix alignment, triggered by a high-ranked constraint against stressed stem-final syllables. The talk has two main goals: to reintroduce Washo as a case of phonologically conditioned affix order and to show that an analysis in Stratal Optimality Theory offers a particularly interesting set of options and restrictions in accounting for PCAO.