Chapters 11 and 12 have the same principal objectives, namely, to introduce mainstream therapies, their history, underlying theory, and the treatment process and technique. To some degree they are presented as two separate but neighboring chapters simply to avoid an overly long single chapter. Aside from this minor, organizational reason, a second and more substantive reason for the breakdown is to cluster together those therapies that one can crudely subordinate under the broad title of “cognitive-behavioral therapies” where the intention is to change behavior using learning and cognitive theories of behavior control. Another key feature shared by the treatment approaches described here is that they are particularly suitable for empirical testing regarding their effectiveness.