BACKGROUND : The state of populations' health is linked to their access to quality healthcare. Best achieving this primary condition - a health, social and humanitarian condition - is an ongoing public policy objective. Although significant effort goes into this, do public policies sufficiently take into account the state of health of the most vulnerable populations? In France, reducing the non-take-up (NTU) of healthcare is a priority in current national health insurance policy. Under the local plans to tackle non-take-up, lack of understanding and exit from the system (PLANIR), national health insurance is currently rolling out a regional and partnership-based intervention framework in order to prevent NTU of healthcare by welfare clients. This social investment is unprecedented, yet the impact of the framework on the most vulnerable populations still seems to be limited. METHODS : The study of this example is based on monitoring of the framework's general implementation. This task was entrusted to the research team co-founded by the author, ODENORE (Observatory for the Non-take-up of Social Rights and Public Services). It is organized in four parts: quantitative monitoring of the detection and addressing of non-take-up situations (n=160,000 questionnaires); analysis of the results through qualitative interviews with beneficiaries and individuals who rejected the framework (n=365 interviews); analysis of the framework's implementation, using qualitative interviews and participant observations at the services in charge of the framework's implementation (n=18 collective interviews across three sites), and an analysis of the partnership through collective interviews with all the actors in the areas involved in the framework (three sites). RESULTS : The analysis shows that the integration of the most vulnerable populations' state of health into a common-law framework for intervention is hindered by three limitations: the framework's neutrality regarding public decisions and non-decisions that exacerbate social and regional health inequalities; its organizational design, which does not take into account the need for long-term medical-psycho-social care; and the absence of regulation capable of bringing together and coordinating the actors working towards healthcare access locally but with different populations. CONCLUSIONS : The difficulties of integrating the most vulnerable populations into a common-law framework such as the one proposed by the national health insurance do not seem insurmountable-provided, that is, that the regulatory authority (the regional health agencies) are willing and able to make it a strategic organizational objective at local level.