The 1990s were declared by Congress to be the "decade of the brain." This declaration is important to all psychologists, not only neuroscientists, because with this declaration come expectations of the cognitive and behavioral sciences generally and because the brain does not exist in isolation but rather is a fundamental component of developing and aging individuals who themselves are mere actors in the larger theater of life. This article examines the importance of a multilevel, integrative approach to the study of mental and behavioral phenomena in the decade of the brain, reviews how this approach highlights the synergistic relationship between theoretical and clinically relevant research, and illustrates how this approach can foster the transition from microtheories to general psychological theories.