This qualitative study tracks the journeys of four career changing women in STEM fields as they pursue a Master of Arts in Teaching degree and transition into teaching positions. Through analysis of archived writing, journaling, photo elicitation, interviews and member-checking, the study analyzes participants' thinking and learning at the beginning of their entrance into graduate school through to their second year of teaching. Using Mezirow's Transformative Learning Theory, the study focuses on the challenges faced by the women, the catalysts for change, the durability of lessons learned in the teaching program and their degree of contentment with their decision given the liberty of hindsight. The study revealed that these women, who were mature, well-educated, mothers and experienced businesswomen, engineers and researchers, underwent dramatic changes in the way they perceived themselves and their views on teaching. The study also demonstrated that Transformative Learning Theory is a useful lens through which to analyze student growth, however, the theory falls short of allowing for a clear understanding of the role emotion plays in transformation. Recommendations are made based on understandings gained from this phenomenological case study regarding the evaluation of effective teacher education programs. A preliminary framework is suggested for use as an evaluation tool for teacher education programs. Most relevant, is the recognition that career changers, like traditionally-aged graduate students, benefit from participating in carefully designed full-year graduate programs including a spiraled curriculum with an experiential, authentic, collegial and reflective framework. Based on the findings of this study, the author suggests that career changers need time, support and experience in order to successfully transition into their role as teacher.