The modern synthesis in evolutionary biology is taken to be that period in which a consensus developed among biologists about the major causes of evolution, a consensus that informed research in evolutionary biology for at least a half century. As such, it is a particularly fruitful period to consider when reflecting on the meaning and role of chance in evolutionary explanation. Biologists of this period make reference to “chance” and loose cognates of “chance,” such as: “random,” “contingent,” “accidental,” “haphazard,” or (...) “stochastic.” Of course, what an author might mean by “chance” in any specific context varies. In the following, we first off er a historiographical note on the synthesis. Second, we introduce five ways in which synthesis authors spoke about chance. (shrink)