Established in 1913, the Siam Cement Public Company Limited (SCG) has grown from a business supporting the development of Thailand's national infrastructure to a leading player in ASEAN and a role model for sustainable development. This chapter discusses how this listed conglomerate incorporates sufficiency thinking deeply into its management practices and policy decision-making. Key factors include a focus on virtues (core values) throughout the organization's culture, prudence via risk management, and a focus on stakeholders as the Sufficiency Economy Philosophy advocates. Results of semi-structured interviews with a range of stakeholders, combined with secondary data from diverse sources, show that sufficiency thinking guides management via its three components of moderation, reasonableness and prudence, based on knowledge and virtue. The SCG case provides a model of sustainability in a large corporation that deliberately decided to embrace sufficiency thinking following the 1997 Asian Financial Crises.