This chapter explores the concept of sustainable consumption by examining how consumer behavior shapes and is shaped by the pursuit of sustainability. It defines sustainable consumption as a balanced approach that meets present needs without compromising future generations, and highlights the inherent tension between infinite human desires and finite planetary resources. The chapter analyzes the stages of sustainable consumption—before, during, and after purchase—and reframes the classic 5W marketing questions (Who, What, Where, When, Why) in a sustainability context. It introduces the concept of “wallet voting,” emphasizing the power of consumer choices in driving social and environmental impact. The chapter also presents a framework for identifying and addressing gaps in sustainable behavior, such as the transitions from ignorance to awareness, attitudes to intentions, and intentions to actions. Psychological effects—including self-licensing, cognitive dissonance, the halo effect, the mere-measurement effect, the bandwagon effect, and confirmation bias—are discussed as key influences on sustainable consumption. The chapter concludes by emphasizing the need for both individual mindset shifts and systemic changes to achieve meaningful progress toward sustainability.