This article focuses on the role of congruence in Creole formation and development, using a competition-and-selection framework. The proposal is that the similarities (the congruent features) that speakers perceive between the languages in contact are favored to participate in the emergence and development of a new language. Specifically, I illustrate how morphosyntactic and semantic features are more likely to be selected into the grammatical makeup of a given Creole when they preexist and are shared by some of the source languages present in its linguistic ecology. This is empirically supported in this article by numerous case studies and a survey of congruent features in twenty contact languages across nineteen grammatical and lexical domains. In order to show how congruence operates, I propose a model of matter and pattern mapping, adapted to the multilingual setting in which Creole languages emerge.