Of the 21st century, new challenges to health and well-being of the Thai society are rapid aging of the population, change of disease pattern i.e. a significant from communicable diseases to non-communicable diseases, increase in number of disabled and major social shifts such as rapid urbanization and dispersion of support systems, substantial migration, increasing work-force participation among women and family structure transformation from extended family to nuclear family. Because rapid urbanization is one of the major social shifts, which relates to increase of non-communicable diseases and other social changes, enhancement of health and welfare systems in the city area in the face of these challenges should be focused in the first place. Existing community services and primary health care approach, which has been implemented after the Alma-Ata conference in 1978, were designed for essential elements particularly preventive measures against communicable diseases, promotion of food supply and proper nutrition, adequate supply of safe water and basic sanitation, maternal and child care, provision of essential drugs and appropriate management of common health problems. Since 1978, the major strategies for implementing primary health care in Thailand are a population-based approach using community intervention/campaign, promoting community participation via community health volunteers and set up community health centres to provide services including maternal and child care, immunization and basic treatment. However, these strategies do not adequately meet new challenges from growing prevalence of non-communicable diseases and disability among the aging society, Hence, new strategies to meet new health challenges are needed. In order to work out a new strategy, a participatory action (operational) research, called the “Bangkok 7 model”, has been conducted in a city area of Bangkok since July 2002. This project is a result of collaboration among three institutes- the Bangkok Metropolitan Administration (BMA), the Chulalongkorn University (Faculty of Medicine) and the King Chulalongkorn Memorial hospital. It was fund by the Health Systems Research Institute and the King Chulalongkorn Memorial hospital. The main objective of the Bangkok 7model project was to establish a new model of health and welfare provision, founded on community health workers and professional health care workers who would integrate across functions of health and social care and work closely with all existing informal cares, whether family, friends or neighbors, and also with voluntary groups and individual volunteers. This model also was to demonstrate a practical way of integration between comprehensive home-based services. which requires interdisciplinary cooperation and community interventions, which requires intersectoral collaboration. (i.e. Community Health Service System) It was hoped that this would enable a system of comprehensive and integrated health care to develop, which was more sensitive and responsive to informal care and able to mesh in with and support it more efficiently and take account of the reciprocal nature of informal care. It was also hoped that such a system would be more amenable to a degree of control by local people and enable them to participate actively in the planning and running for the health and welfare system in the city area. The community health service system is viewed as an expansion model of conventional community-based health care in Thailand, which bases on four basic principles of the primary health care approach including-(i) universal accessibility and coverage on the basis of need, (ii) community and individual involvement and self-reliance, (iii) intersectoral action for health, and (iv) appropriate technology and cost-effectiveness in relation to the available resources. The community health service system is also viewed as the strategy of enhancing accessibility of individual and community to the health system. Thus it is the first level of contact of individual and community under the primary health care approach. The community health service system is comprised of various comprehensive activities for all ages, which promote integration between formal and informal care to serve eight basis elements including - (i) Health promotion and education (ii) Prevention and control of communicable diseases and other endemic health problems such as drug addiction, accidents and injuries, alcoholic intake, occupational health problems (iii) Environment, water and sanitation (iv) Maternal and child health care and family planning (v) Food supply and food safety (vi) Management of chronic diseases, which emphasizes on adherence to treatment (vii) Basic treatment and rehabilitation for health problems including disabilities (viii) Long-term care The community health service system has to provide integrated health and social services for needed individuals and families at their own homes (i.e. home-based services) and community interventions/activities (i.e. community-based services). These two kinds services must be integrated and complement to each other. While intersectoral collaboration is essential for success of community-based activities, interdisciplinary collaboration is vital for home-based care and its support activities. The Bangkok 7 model was developed in 2 districts at the heart of the Bangkok Metropolitan, of which total population was around 60,000. These 2 districts are the responsible areas of the 16th public health centre of the Health department, BMA. The 16th public health centre, a community health centre, is the principle organization of the Bangkok 7 model which provides the community health service for people in its catchments area. The King Chulalongkorn Memorial hospital joins the Bangkok 7 model as a referral centre and also as a partner of model development. The Bangkok 7 model composes of home-based service system and community-based service system. The home-based service system is comprised of activities including regular home visit, home assessment, home nursing, home rehabilitation, home education/counselling, service for treatment adherence of selected chronic diseases (diabetes mellitus, hypertension, tuberculosis), social service and palliative and end of life care. These home-based services are supported by activities/services in the 16th Public Health Centre including multidisciplinary team meeting, outpatient services, rehabilitation services, well baby clinic, ANC clinic, family-planning service, acupuncture clinic, social services and care. Community participation is vital for both home-based service system and community-based service system. Health volunteers and community leaders are invited and encouraged to join in every step of activities and planning. After on year, the Bangkok 7 model has been successfully developed. Its output is presented to the administrators of the BMA and the Health department. Its responsibility in term of management was fully transferred to the Health department of the BMA on the 1st October 2003 and the whole system was maintained and carried on. Its success was disseminated to the public through mass media such as newspapers and televisions. The Bangkok 7 model and its output was the main topic of several academic conferences in Thailand. However, the obvious sign of success comes from the Health department as it starts to adopt the Bangkok 7 model for implementation in other areas. This study demonstrates that the Bangkok 7 model, the innovative community health service system for achieving the integration of health and welfare systems is a new strategy in health service system to meet new health challenges in the city area of developing countries like Thailand. It provides strengthening of formal-informal link, which is essential for long-term care, and intersectoral collaboration. Its underlined principles, system design and development management would benefit for further development focuses on the primary health care and health and welfare systems. However, it is not the ideal model that benefits with all kinds of population and areas in Thailand. Administrators and health care providers of other areas, including both urban and rural areas, should workout how to adopt or apply the Bangkok 7 model into their own practice.