This chapter reviews the evidence concerning the efficacy of psychostimulants as cognitive enhancers in healthy and non-clinical individuals. Cognitive operations are the mental processes whose outcomes affect mental content in one or more areas of cognition. Cognitive functions are typically modulated by non-cognitive factors such as mood, level of energy, motor function, impulsivity, and motivation. Cognitive enhancement is an intervention that improves or augments one or more cognitive domains, such as learning, memory, or attention. Psychostimulant is a behavioral description for drugs that elevate mood, increase motor activity, increase alertness, allay sleep, and increase the brain's metabolic activity. Psychostimulants are a large class of drugs with broadly overlapping neuropharmacological properties, mechanisms of action, and therapeutic effects. The class of psychostimulants most commonly reported for use as cognitive enhancers is that of amphetamines. Amphetamines influence both dopaminergic and noradrenergic systems.