This chapter focuses on why collaboration between CLIL teachers is important and necessary for effective and rewarding CLIL implementation. This chapter outlines different forms of collaboration developed across CLIL education contexts and addresses the ways in which encounters between teachers have been conceptualised to-date. This chapter also introduces tools helpful for negotiating and developing collaborative relationships and exemplary partnerships that can inspire and support collaboration between CLIL teachers. The chapter closes with implications for research and practice regarding collaboration between CLIL teachers.