Introduction The objectives of the Breakthrough Series Collaborative are to close the gap between what we know and what we do, and to contribute to continuous quality improvement (CQI) of healthcare through collaborative learning. The improvement efforts are guided by a systematic approach, combining professional and improvement knowledge.

Objectives To explore what the improvement teams have learnt from participating in the collaborative and from dealing with promoting and inhibiting factors encountered.

Method Qualitative interviews with 19 team members were conducted in four focus groups, using the Critical Incident Technique. A critical incident is one that makes significant contributions, either positively or negatively, to an activity.

Results The elements of a culture of improvement are revealed by the critical incidents, and reflect the eight domains of knowledge, as a product of collaborative learning. The improvement knowledge and skills of individuals are important elements, but not enough to achieve sustainable changes. 90% of the material reflects the need for a system of CQI to solve the problems that organisations experience in trying to make lasting improvements.

Conclusion A pattern of three success factors for CQI emerges: (1) continuous and reliable information, including measurement, about best and current practice; (2) engagement of everybody in all phases of the improvement work: the patient and family, the leadership, the professional environment and the staff; and (3) an infrastructure based on improvement knowledge, with multidisciplinary teams, available coaching, learning systems and sustainability systems.