This dissertation presents a framework that allows using sustainable marketing as a threshold concept to critically evaluate and question the assumptions embedded in both marketing theory and professional practice. Theoretically, the framework draws on stakeholder thinking, the notions of meaning and discourse and moral philosophy and methodically on action research. The framework is illustrated using two action research studies: one focusing on sustainable tourism product development in a small business context and the other focusing on the use of problem-based learning to promote sustainability learning in an educational context. This research offers a more comprehensive understanding of sustainable marketing by shifting the analytical focus to the market as a complex web of stakeholder relationships and sustainability as a set of meanings and values that are socially constructed through the discourses and practices available within a particular market context.