Assimilation or agreement between consonants at a distance
 has two key properties. First, it preferentially targets
 similar consonants and second, intervening segments do not
 participate. It is argued that this agreement arises
 through correspondence relations between consonants
 rather than via feature spreading, allowing for a unified
 analysis of feature spreading as strictly local.

Similarity of consonants plays a central role in

determining which consonants stand in correspondence. 
 A typology of consonant agreement reveals four main 
 classes: nasal, laryngeal, coronal and liquid. Case studies
 of nasal agreement and laryngeal agreement are presented
 and the implications of the proposal for coronal agreement
 are discussed.