Gender fulfills two different functions, i.e. nominal classification and crossreference of constituents through agreement. Besides the generally acknowledged possibility of a grammaticalization process that may lead classifiers to become gender markers, gender systems may also arise as a consequence of special agreement patterns connected with differential marking of core arguments. It is argued that different origins of gender systems imply higher relevance of either function of gender in individual languages, and that this may have consequences on the values of gender within specific gender systems.