Background: Improving the healthcare for patients with depression is a priority health policy across the world. Roughly, two major problems can be identified in daily practice: (1) the content of care is often not completely consistent with recommendations in guidelines and (2) the organization of care is not always integrated and delivered by multidisciplinary teams. Aim: To describe the content and preliminary results of a quality improvement project in primary care, aiming at improving the uptake of clinical depression guidelines in daily practice as well as the collaboration between different mental health professionals. Method: A Depression Breakthrough Collaborative was initiated from December 2006 until March 2008. The activities included the development and implementation of a stepped care depression model, a care pathway with two levels of treatment intensity: a first step treatment level for patients with non-severe depression (brief or mild depressive symptoms) and a second step level for patients with severe depression. Twelve months data were measured by the teams in terms of one outcome and several process indicators. Qualitative data were gathered by the national project team with a semi-structured questionnaire amongst the local team coordinators. Results: Thirteen multidisciplinary teams participated in the project. In total 101 health professionals were involved, and 536 patients were diagnosed. Overall 356 patients (66%) were considered non-severely depressed and 180 (34%) patients showed severe symptoms. The mean percentage of non-severe patients treated according to the stepped care model was 78%, and 57% for the severely depressed patient group. The proportion of non-severely depressed patients receiving a first step treatment according to the stepped care model, improved during the project, this was not the case for the severely depressed patients. The teams were able to monitor depression symptoms to a reasonable extent during a period of 6 months. Within 3 months, 28% of monitored ...