Learning an L2 is often said to transform an individual into a new (and improved) version of the self. This mixed-method study investigated (1) whether, and if so, in what way such a transformation occurs within the L2 learner self; and (2) whether current theories of self and motivation in the fields of SLA and psychology adequately address L2 learner selves across the learning trajectory. The study was grounded in and critically examined the L2 Motivational Self System (L2MSS) by Dornyei (2005, 2009) as well as psychological theories of possible selves (Markus & Nurius, 1986) and of the self and self-concept (Oyserman et al., 2012). Six intermediate-level learners of L2 German at a large Midwestern research university were asked to report their likeness to eight language user profiles (vignettes) across five salient timepoints of reference in a language learner's trajectory. The ratings together with statements from interviews were analyzed in regard to different self-concepts, including the dimensions of ideal self and ought-to self from the L2MSS. Results revealed the need for a holistic understanding of the L2 learner, including the importance of past selves, in order to further understand the on-going motivational processes that guide the L2 self. The dimension of the 'retired self' is introduced, a self-concept that consists of a once possible self that has since been retired in favor of others but that still serves as motivational. Findings further suggest that the learner self is constructed through dynamic and situated fore- or backgrounded self-concepts. On the basis of these findings, an emergent model of the L2 self is proposed that combines the dynamic nature of self-concepts with the continued L2 learner trajectory, which offers one possible explanation for feelings of transformation through L2 learning. Results affirm the need for a continued investigation into the L2 self and the link between self and motivation through the integration of current psychological theory into second language acquisition research. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]