Motivation, the drive to perform goal-directed actions, is necessary for healthy human functioning. Impaired motivation is a prominent symptom of neuropsychiatric disorders including schizophrenia (SZ) and depression and is not improved by currently-available therapeutics. Motivation relies on a conserved neural circuit comprised primarily of the ventral striatum (VS), ventromedial prefrontal cortex, and dorsal anterior cingulate cortex. VS hypofunction has also been linked to negative symptoms of SZ. Thus, it is essential to study motivation in order to translate knowledge of its neurobehavioral mechanisms to therapeutic advances. The overarching goals of this dissertation were to characterize neural activation patterns and behavioral decision-making processes related to motivation across different contexts and to investigate how individual variation in motivation impairment and clinical symptomatology relates to these neurobehavioral processes. First, we investigated effort discounting in healthy individuals and patients with SZ. We found that VS activated to reward and de-activated to effort costs, integrating to encode subjective value. VS activation during task decisions related negatively to dimensional clinical amotivation across patients and controls. Next, we investigated the role of VS in encoding self-generated correctness responses during intrinsically and extrinsically motivated performance of a memory task in healthy adolescents and those at risk for psychosis. We found that VS encoded parametric subjective confidence during memory task choices and parametric prediction error during performance feedback, providing evidence for VS engagement related to intrinsic expected value. VS activation during choice related positively to dimensional self-reported trait intrinsic motivation across both study groups. Third, we employed a novel effort discounting behavioral task to compare motivated decision-making in social and non-social contexts. We found that motivated behavior in social contexts related to both global and social-specific motivation and related to approach and avoidance motivation tendencies. Together, this dissertation work sheds light on how expected value is computed under different motivational contexts—monetary, intrinsic, and social—and how each of these processes relies on global vs specific neurobehavioral mechanisms. Our findings on the effects of individual differences in these motivation processes will enhance future abilities to detect novel treatment targets for impaired motivation.