There is a well-established asymmetry in the behavior of medial consonant clusters: the first consonant in the cluster can undergo assimilation or deletion, but the second consonant in the cluster cannot. This article presents an explanation for that asymmetry based on a version of Optimality Theory with candidate chains (McCarthy (2006a)). The key idea is that a consonant can only assimilate or delete if it first loses its place features by debuccalizing, and debuccalization is only possible in coda position.