Over the years much effort has gone into clarifying lithium's mechanism of action. It has been well-documented, and reviewed in the present symposium, that the effects of lithium on the human body are widespread, however it remains unclear which of the many effects is the one which mediates clinical benefit. One of the obstacles to progress has probably been an incomplete integration of clinical and laboratory approaches to the problem. In this paper we briefly summarize the main observations in the clinical dimension. The best-documented clinical effects of lithium have been mood stabilization, antimanic effects and antiaggressive action. Several other effects have, however, been observed and reported, some still controversial but all deserving our attention. We conclude that one can observe not one but several distinct, qualitatively separable benefits, with different clinical characteristics. It appears important that in any future laboratory search for the relevant mechanisms of action of lithium, we keep this clinical multiplicity in mind.