In this chapter, I will (1) review the concept and function of projective mechanisms on a psychodynamic basis. In this section, I will outline the relation of projection to the unconscious, its use in innerpsychic dynamics, and the underlying mechanisms for its use in psychotherapy like creativity, imagination, and symbolization; (2) give an overview over the use of projective methods for testing and diagnosis in the psychological sciences; and (3) exemplify the use of projective methods in diagnostics and psychotherapy of children and adolescents. I will present current methods based on drawing, verbally describing and imaginating, and playing arts, focusing on sand play therapy and miniature figure play.Keywords: projective methodology, object relation theory, sandplay therapy, figure play, operationalized psychodynamic diagnostics in children and adolescents (OPD-CA-2), thematic apperception tests, narrative1. Concept and function of projective mechanisms 1.1. The relation of projections to the unconscious The Latin word "proiectus" means "to throw forth," or "to cast forward," and with regard to psychological sciences, several definitions have been provided. First of all, Sigmund Freud [1] described the "classical" projection as defense mechanism when the ego is threatened and refuses to acknowledge the trait, it attributes the trait to the outside world [2]. Later on, Freud broadened his view of projective mechanisms and refers the term projection to a general primitive mechanism, not only a defense mechanism, implying that projection may also be present when there is no conflict [3].In this sense, the attributive projection can be understood as "ascribing one's own motivations, feelings, and behavior to other persons" [2]. This definition seems to be the most common, but © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. also the most (over-)simplified one. There seem to be no relations to psychoanalytical concepts of the self, or the unconscious. Most authors use this term to describe "any kind of externalization" [2] with a correlation between characteristics of the proband and predictions or statements issued. The attributive projection is mostly similar what Horney called the "naïve" projection, which means that the subject assumes that others think, feel and behave in the same way as oneself [4]. Today, this view can be integrated into the concept of mentalization.In a third view, Murstein introduced the autistic projection as "perceived aspects of another person which are modified to accomplish own needs [2]."In the fourth mode of rationalized projection, the process of projection lies in the unconscious, but the projector is conscious of his/her behavior. In this context, the rationalized projection can be understood as "defence against guilt [2]," ...