The olfactory system represents the most acute and phylogenetically oldest device that the majority of organisms have to know their physical and social environment. In humans, however, the most predominant functional sense is sight, by virtue of an evolutionary path that has strongly limited the role of olfaction in decision making, social behavior, and cognition. The predominance of sight over smell in humans has important neurobiological, behavioral, and cognitive implications, which are discussed here in a comparative perspective. We propose a theoretical framework in which the psychological determinants of olfactory perception-phenomenological aspects, neuropsychological structures, emotional/affective correlates, cognitive mechanisms, decision-making dynamics, and behavioral outcomes-are coherently connected and integrated. Implications of this theoretical framework for research and for clinical and diagnostic practice are discussed. (PsycInfo Database Record (c) 2020 APA, all rights reserved).