This study is a qualitative inquiry of eight mid-career second language (L2) teachers’ identity evolution. These teachers have or had full-time or tenured teaching experience in secondary schools in Japan. Since they were mid- and later career teachers, they have explored their development, what they are now, and why they keep growing. They have all made meaningful voluntary changes in their professional lives. To make meaningful voluntary changes at moments of transitions, the teachers have made choices and negotiated, or juggled, their identities. They are successful teachers who have tenaciously pursued what matters to themselves professionally throughout their lives. One unfilled niche in the L2 teacher development and education is research on redefining L2 teachers who began their careers in secondary education in Japan, make meaningful voluntary changes in mid-career, and make apparently difficult work situations negotiable. The three purposes of this study are to (a) explore why and how L2 teachers’ identity evolution and their professional growth at mid-career happen; (b) learn more about the complexity of teacher change mechanisms at mid-career, and; (c) highlight ways that teachers whose professional development has stalled can grow out of their stagnation by examining the lives of successful mid-career and later career teachers. Eight L2 teachers participated in this study, recruited between 2005 and 2010. Interviews are the main source of data collection. I triangulated the data with email exchanges, class visits, and public documents such as Curriculum Vitae, syllabi, and curriculum descriptions given to students in a current or former class, handouts used in class, and published research articles. The data analysis was grounded in Riessman’s (2008) thematic and structural narrative analysis for identity evolution. Using these frameworks, I analyzed the data by(a) looking for stories and events in the telling as well as searching for identity negotiation and evolution with the participants with thematic analysis, which applied to all the participants, and (b) seeking contextual, discursive, and interpersonal cohesion and meanings with structural narrative analysis, which was applied to one participant. What each participant deemed important determined what kind of L2 teacher they wanted to become. With their efforts to keep evolving as L2 teachers through reflection, action, and negotiation they became consciously aware of what mattered to them. Their conscious awareness prompted them to exercise agency to plan meaningful changes. / Teaching & Learning