This qualitative case study explores how implementing mandated collaboration in the workplace impacts teachers' professional practices based on the experience of primary school teachers in Ethiopia. The study adopted a constructivist orientation, which prompted the use of qualitative methods of inquiry, and data were collected through eighteen one-to-one interviews and three focus group discussions (FGDs). The findings indicated that implementing mandated teacher collaboration might be helpful in the early stages of teacher collaboration as a starter from which a voluntary and authentic collaborative culture emerges, yet it is not necessarily a good thing once collaborative practices are well initiated. That means, despite its potential for fostering teacher professional learning, mandated collaboration can be a threat to the professional autonomy of teachers; it can also intensify conflict, nurture groupthink, and promote social loafing among teachers.