In view of recent changes in both migration patterns and urban labour market conditions, the permanent settlement migration paradigm has become insufficient to guide our understanding of rural-to-urban migrant workers in China's market transition. Using Shenzhen City as a case study we consider migrant workers as enabling agents who interact with the urban labour market.We therefore examine the ways that migrant workers' social capital accumulation, migration experience, and job mobility influence urban labour market dynamics. In painting a picture of migrant workers we complement existing institutional and labour market analyses. As we demonstrate, by frequently changing jobs and destination cities, migrant workers accumulate social and human capital so as to improve their opportunities in the urban labour market. This is evidenced by migrants' improved occupational positions and increased wage earnings.