Despite progress on extending social health protection coverage, most low-income countries are still far from achieving universal health coverage and thus key objectives related to improvements in health, such as those aimed at by the Millennium Development Goals (MDGs), will almost certainly not be realized by 2015. Principally affected are the most vulnerable populations: the rural and urban poor and workers in the informal economy and their families. It is of particular concern that progress might not only remain limited but even be reversed if policies continue to fail to address the root causes of gaps and deficits in health coverage. This article provides evidence that these causes lie both within and beyond the health sector and are strongly related to poverty and other forms of vulnerability. It argues that sustainable progress towards universal health coverage can only be achieved in an adequate time frame when focusing simultaneously on i) extending health coverage and improving access to needed health care; ii) providing income security through income support to those in need; iii) addressing limitations, or the inability to participate, in income generation from work; and iv) implementing coherent policies within and across the social, economic and health sectors that set priorities on poverty alleviation. Such policies can best be implemented in the context of national social protection floors (SPF) that focus on access to at least essential health care and on providing at least basic income security over the life cycle to all in need. Implementing SPFs may result in breaking the mutual linkages between ill health, poverty and other vulnerabilities and achieving sustainable progress towards universal health coverage and other social protection objectives.