This study gained insights into how the secondary education expansion policy shaped teacher identity. A qualitative case study design was adopted, and interviews and document analysis were used for data gathering. The main participants were teachers and school principals from the Iringa region, Tanzania. It was revealed that the inadequate policy enactment adversely affected teachers’ own perceived teaching aptitudes, and intensified them to behave unprofessionally. These issues prompted the teaching profession to lose social standing. The study adds to a growing body of literature on how teachers “construct” what secondary expansion means for them as both effective and ethical professionals.