Animals may be careful in their choice of mates for a variety of reasons. The ideal mate may have to hold valuable resources as well as being highly fertile or fecund. As likely as not, it should be neither too closely related nor too distantly related, and it should be maximally attractive. All these aspects of a member of the opposite sex may influence how many descendants the pair could produce, but the importance of each will usually depend on the sex and the species of the individual making the choice. This book brings together modern thinking on the various functions of mate choice and its role in evolution. The ways in which finely tuned preferences for a particular member of the opposite sex develop are described, as is the importance of compatibility between mates in long-lived species. Finally, the book deals with the underlying mechanisms and the decision rules involved in choosing a mate. The different approaches of the authors combine to make an excellent overview of an attractive and fascinating topic. The book is particularly directed at students, teachers, and research workers, who are interested in evolution and behaviour, but the surveys it contains will be of considerable use to others whose main field of interest is in the social sciences.