In today’s Mexico, approximately 50% of children experience multidimensional poverty, with Indigenous children particularly affected; half of them live in extreme poverty and nearly all lack access to social security. The current political landscape threatens to exacerbate these issues. Reductions in public spending and the dismantling of federal child health programmes are likely to further hinder children’s development, well-being and health by limiting access to vital services like childcare, education and healthcare. Children’s hospitals in Mexico may increasingly depend on philanthropy and civil society support, however, the relationship between the State and the philanthropic sector is not without problems. This paper presents a case study of ‘social assistance’ in Mexico, by exploring the structure and organisation of two non-for-profit groups and their relationship with a children’s hospital and healthcare staff in the southeast of Mexico through semi-structured interviews and document analysis. It aims to explore the challenges and tensions that arise in the collaboration between the State and philanthropic organisations, particularly in the context of sustaining and enhancing children’s hospitals. Our study reveals that the philanthropic sector has tried to compensate for some of the enormous needs that historical and more recent challenges imply to the most vulnerable families when seeking medical attention for their children. However, philanthropic efforts are ultimately sustained by the same families through a ‘co-responsibility model’. There is an urgent need for public policies based on human rights and social reform, which simplify bureaucratic processes and support philanthropic organisations in aiding vulnerable groups beyond the healthcare system’s scope. Our case studies suggest that today philanthropic organisations not only complement the activities of the public health system by giving support to the families of the patients, but also substitute the State in the delivery of very basic medical care people should have the right to receive.