This monograph explores the impact of two personality traits (consumer optimism and consumer pessimism) and three cognitive processes (consumer environmental, health and social consciousness) on sustainable consumer behavior. Drawing on survey data collected from Poland, China, and India, the study examines how these traits and processes interact, and how demographic factors such as consumer age, education, income and household size moderate these relationships across different cultural contexts.Surprisingly, the findings reveal that not only optimism, but also pessimism can directly and positively influence sustainable behavior. This unexpected result for consumer pessimism challenges common assumptions and opens new avenues for understanding the psychological drivers of sustainable consumption.With theoretical insights and practical implications for marketers and policymakers, this monograph offers a fresh perspective on the complex nature of sustainable consumer behavior.