One criticism of educational research is few studies examine the sustainability of professional development for teachers. This study grew out of a pilot study conducted in 2005 with a group of teachers who participated in the Shakespeare Lives! professional development program. The purpose of this qualitative collective case study was to determine whether the changes that teachers initially reported in 2005 were sustained three years later, as well as whether these changes were transformative. Data collected in this study were conceptualized through the lens of transformative learning theory. Data sources included: (1) archival data from the 2005 pilot study, (2) quick-writes in which each teacher reflected on a statement he/she made in 2005 about change, (3) artifacts that represented each teacher’s teaching (4) digitally recorded interviews, (5) email responses to interview follow-up questions. Findings indicate that three levels of transformation exist: pedagogical, professional, and personal. All of the teachers experienced pedagogical transformation, four teachers experienced professional transformation, and two teachers experienced personal transformation. Implications for teacher professional development as well as suggestions for further research are discussed.