Abstract Since 2010, the National Agency for Education has had an intention to improve teaching and learning in schools by introducing collaborative structures. In order to develop a learning school organisation, with the aim that all students are able to reach their educational goals, shared responsibility and common learning is advocated. The study focuses on a school´s implementation of teaching learning communities (TLC) based on teachers´ engagement in systematic collaborative work. The theoretical framework is based on social- culture perspectives. The aim of the study is to explore important conditions as well as success factors which can be related to a TLC work. The analyses are based on nine interviews and findings indicate that challenging factors are; the importance of leadership, a democratic collaborative structure and the teachers´ attitudes towards professional learning. The success factors indicate that a collaborative teaching learning is possible by challenging each other’s ideas and practices, a development of professional language, increased self-esteem and the improvement of teacher´s relations and new perspectives according to teaching and pupil´s learning. The study indicates that a demanding factor for a well-performing teaching learning community is based on a well-organized leadership. Leaders ought to be aware of how democratic processes might threaten collaborative work and how a successful leadership is formed.