This chapter introduces another important constraint on mate choice; namely, that choosers are the object of choice themselves. It focuses on the mechanisms underlying mutual mate choice, notably how preferences are dynamically adjusted in light of the chooser being the chosen. It begins with the simplest form of mutual mate choice, when individuals reciprocally prefer each other's phenotypes. It then turns to the widespread phenomenon of mutual mate choice in systems that are socially promiscuous: both males and females mate multiple times, but both males and females express preferences for particular phenotypes in the opposite sex. Mutual mate choice becomes more constrained in social monogamy, where one can only be paired with a single partner at a given time. The chapter discusses how partners reach pairing decisions and how pair bonds are maintained and transgressed in both hetero-and homosexual couples. Finally, it briefly covers the interesting case of mate choice in hermaphroditic species.