In versified texts, congruence is one facet of the concordance between the edges of metrical constituents and those of grammatical constituents. Congruence may be characterized roughly as the requirement that no element within a syntactic constituent be in a stronger metrical position than the final element in that constituent. If break strength is defined in terms applicable to any constituent structure tree, syntactic as well as metrical, incongruences are discrepancies between the relative strengths of two breaks in metrical structure and the relative strengths of their counterparts in syntactic structure. Although our primary source of data is classical French verse, the characterization of congruence we present is a rather abstract one that does not make reference to features that are specific to French poetic forms or to the grammatical structure of the French language. This should make this characterization applicable in other poetic traditions.