In the developing world informal employment is not generally regarded as illegal or irregular, but as a standard way of life and income-generation. Informal employment represents a significant share of employment in developing regions: ranging from 86 per cent in Africa, to 68 per cent in Asia and the Pacific and 69 per cent in the Arab States. The result is extremely low levels of social security coverage, both quantitatively and qualitatively. And yet, especially in the last few decades, unprecedented steps have been taken to extend social security coverage to informal workers. These developments have largely been informed by economic considerations and shifting social, cultural and conceptual perceptions. Conceptual and regulatory adjustments in areas affecting the very notion and purpose of social security, its sphere of coverage and some of the actors involved have been paramount. Innovative institutional mechanisms, flexible design arrangements and a supportive environment have helped to inform social security extension to these workers. These adjustments and developments challenge the traditional boundaries of the social security notion, aims, structures and mechanisms. This contribution critically reflects on the rationale for and nature of these extension modalities.