This chapter addresses an important issue in that caffeine research may be more revealing if studies are carried out on tasks involving multicomponent skills and employing functional settings in which the subject’s active and effortful participation is ensured throughout the testing session. Caffeine's effects upon human performance depend upon a variety of factors, such as habituation to caffeine, basal arousal and initial response level, adequacy of experimental design, caffeine dosage, and other factors related particularly to task demands determined by the nature of task and its level of difficulty and complexity. Caffeine might lead to an alteration in the function of a central selective process that governs various ongoing cognitive operations. Investigation of caffeine effects on a task that requires active and effortful participation of the organism, on the one hand, and depends heavily upon more than one component of performance on the other would certainly be more useful and helpful in understanding the subtleties of caffeine effects on behavior.