A number of contemporary neurobiologic, neuropsychiatric, neurologic, and neurosurgical aspects of basal ganglia research are reviewed in this issue. Remarkable progress is evident in nearly every area of endeavor. In this concluding article, the authors have selected four areas for discussion, which touch on a range of promising research strategies, and highlight a few of the present controversies in this field. The article begins with a discussion of the promise of behavioral analysis across mammalian species as a means of studying the functional anatomy of the basal ganglia, and its role in learning and memory, as well as other forms of cognitive processing. Second, the authors considered some of the competing views of how the structural organization and circuitry of the basal ganglia relate to the learning and performance of behavioral routines. Third, a range of genetic and developmental perspectives on basal ganglia function are considered. In closing, the authors return to a discussion on the relevance of these complex neurobehavioral systems, and the understanding and treatment of psychiatric and neurologic disease.