The microeconomic analysis of labour mobilisation and labour relationships in developing countries, though diverse in its hypotheses, methods and results, still nurtures the idea of dualistically segmented labour markets. This binary rural/urban segmentation leaves in the dark an important stratum of developing countries' labour markets, namely the urban informal sector. How does this huge group of unprotected workers gain access to jobs? Do labour relations comprise a social security dimension? We focus on the contractual forms that unregistered employment relationships take. We successively explore the content of employment relationships and compare it to existing classifications. We also assess the role of friends and families in accessing jobs and the changing social embeddedness over time of labour arrangements to highlight the crucial importance of interpersonal ties for informal work trajectories