Introduction: Finland is currently preparing an extensive national-level reform to integrate its social and health care systems at all levels to achieve client-oriented, effective, cost-efficient and coordinated services.The Better Everyday Life (BEL) project (2015–2017), funded by the Finnish Ministry of Social Affairs and Health, is a pilot project implementing the principles of the forthcoming reform at the operative level. Aim and theory of change: The aim of the BEL project is to support high needs/high costs clients in everyday life by developing client-centered, integrated care for them. Theoretically the project draws on the extended Chronic Care Model. Short description of practice change implemented: Development work on integrated care is done by grassroots professionals, together with the clients. The participants of the BEL project are care professionals working in primary care, secondary care, social care and education (37 multiprofessional and interorganizational teams, altogether 250 professionals). The professionals (nurses, doctors, social workers, therapists etc.) work together in teams, supported by coaches and project seminars, aiming to develop concrete tools for integrated care. The Breakthrough method and other LEAN-related development methods are used. The teams also involve clients in their development work. The BEL project thus serves as a common platform for co-designing integrated care for this challenging client group. Targeted population and stakeholders: Each BEL team has selected its own client group, for example older people who repeatedly visit health care centers, young people with mental and drug problems, unemployed people with several health and/or social problems; the common trait of the group being that they need/use a lot of health and social care services. Highlights: (innovation, impact and outcomes) The concrete tools the BEL teams have developed include - A tool for identifying high needs patients - A comprehensive, shared social and health care plan (SHCP). SHCP should in future be used for all actors instead of different kinds of plans of care providers - Concrete collaboration models to deal with shared clients. The models developed by the teams will define how the concrete collaboration process between ‘silos’ of health and social care proceeds. Comments on sustainability: The project is outlined according to the principles of the forthcoming national reform of the Finnish social and health care system. The sustainability of the project’s outcomes depends, however, on how local managers and decision-makers are committed to the project. Comments on transferability: The challenges related to care for high needs/high costs clients are quite similar in most European countries. Conclusions and Discussions: Identification of high needs clients is difficult if the professionals do not collaborate over the boundaries of care organizations and sectors. Many clients use the services of several care providers, but individual professionals do not know which other professionals are already involved in the care of the very same patient. Lessons learned: It is extremely important to engage grassroots level professionals and clients themselves in the development work and support them to collaborate beyond the traditional ‘silos’.