Time perspective (TP), a fundamental dimension in the construction of psychological time, emerges from cognitive processes partitioning human experience into past, present, and future temporal frames. The authors' research program proposes that TP is a pervasive and powerful yet largely unrecognized influence on much human behavior. Although TP variations are learned and modified by a variety of personal, social, and institutional influences, TP also functions as an individual-differences variable. Reported is a new measure assessing personal variations in TP profiles and specific TP biases. The five factors of the Zimbardo Time Perspective Inventory were established through exploratory and confirmatory factor analyses and demonstrate acceptable internal and test–retest reliability. Convergent, divergent, discriminant, and predictive validity are shown by correlational and experimental research supplemented by case studies.