CAP21 may refer to: * Citizenship, Action, Participation for the 21st Century - a green liberal political party in France. * Collaborative Arts Project 21 - an Off-Broadway theatre company and musical theatre training conservatory. * A version of the Mudry CAP 20, a French single-seat aerobatic monoplane.This disambiguation page lists articles associated with the same title formed as a letter-number combination. If an internal link led you here, you may wish to change the link to point directly to the intended article.