Access to social security is internationally acknowledged as a human right, but in fact is one that is far more honoured in its breach than in its enforcement, and is frequently not readily accessible to the most vulnerable in society. The growth of the informal economy, both in developing and developed countries has exposed the weaknesses and shortcomings inherent in the traditional approach to the provision of social security for those who fall outside of the formal economy. Social security has also traditionally been a vehicle to promote social cohesion and solidarity between different sectors of society, yet it is clear that marginalised workers in the informal economy and the poor in general are often excluded from this solidarity. Through the prism of access to healthcare, this paper seeks to explore some of the reasons for the shortcomings in the current cover of social security, to consider what options exist for extending healthcare provision, and to consider the role that trade unions could play in extending healthcare.