This chapter gives a psychologically robust account of virtuous and vicious intellectual self-trust. Tanesini starts by arguing that intellectual self-trust is a set of dispositions to rely on one’s cognitive faculties, together with positive epistemic feelings and confidence in one’s willpower. She then distinguishes one epistemically beneficial form of intellectual self-trust, confident optimism, and three pathological ones: arrogant, timid, and servile self-trust. Drawing on psychological research, she argues that each form of intellectual self-trust arises from a corresponding form of self-esteem. Confident optimism has its roots in healthy self-esteem, which frees the agent to be motivated in her inquiry by the prospect of achieving epistemic aims. Arrogant, timid, and servile self-trust, by contrast, derive from warped forms of self-esteem that focus the agent not on epistemic goods, but rather on her own vulnerability. Confident optimism about one’s faculties, then, turns out to be an intellectually virtuous form of self-trust, whereas the three pathological forms of self-trust turn out to be intellectually vicious.