SMEs have a substantial potential to improve the sustainability of the modern economy. This book presents three studies on drivers of business sustainability in SMEs. On an individual level, a qualitative study shows how owner-managers incorporate their own sustainability-related identities into their businesses and how they handle any resulting conflicts. On an organisational level, another qualitative study pursues the question of whether and how social capital drives SMEs’ attempts to achieve sustainability. On a network level, a mixed methods study assesses potential success factors for interorganisational sustainability networks with regard to their importance for network success. The book concludes with a cross-level comparison of findings which provides both researchers and practitioners with a comprehensive overview of theories that can be applied in this respect, their main results and potential approaches to future research.