SME's are acknowledged as effective sources of jobs and incomes, gaining an important position in the development agenda, subsequently 'cluster' policies were conceived as a framework to augment the effects of SMEs and to optimize resources used to support them. Based on case studies from Brazil, Vietnam, Indonesia and India, this volume examines SME clusters and argues that unless they counteract common problems such as very low wages, poor working conditions, poor quality products and lack or environmental regulation, they will be pushed out of the market and so become unsustainable. This book suggests that the SME clusters currently being stretched should react by 'socially upgrading' in order to improve their innovation capacity, as well as social, environmental and labour standards. It puts forward conceptual frameworks which explain the way firms can upgrade: through markets, interaction among cluster members, through Corporate Social Responsibility and other such public policy, and through the better enforcement of regulation.