This book looks beyond the conceptualization of urban futures that place the megacity and its slums at the center to examine how diverse groups of migrants (primarily internal Chinese) are producing transient (mega-) urban spaces and impacting the urbanization process. From 2010 to 2012, the author conducted over 120 qualitative interviews with migrants of all categories - voluntary and involuntary, blue collar and white collar, domestic and international, and migrant groups of high risk. The research was administered in the Pearl River Delta (Guangzhou, Shenzhen and Foshan) as part of a larger research program on informal dynamics of megacity development funded by the German Research Foundation (DFG). The study contributes to the current debates on restricting or encouraging migration to Chinese megacities.