The frontal lobe occupies the anterior portion of each cerebral hemisphere. It is the largest of the four lobes and the most recently expanded in evolutionary terms. Its functions include planning, judgment, decision making, voluntary movement, and the regulation of social behavior.

The primary motor cortex at the rear of the frontal lobe issues commands for voluntary muscle activity. Premotor and supplementary motor areas prepare and sequence movements. The prefrontal cortex, further forward, supports working memory, cognitive control, and the evaluation of future consequences. Damage to the prefrontal region—famously illustrated by the case of Phineas Gage—can leave basic intelligence intact while devastating personality, impulse control, and the ability to follow through on plans.

The frontal lobes continue to mature into early adulthood, a fact often cited in discussions of adolescent decision making. They are heavily interconnected with limbic structures, allowing emotion and cognition to influence each other. Many psychiatric and neurological conditions involve frontal dysfunction.

When a person weighs options, inhibits an impulse, or initiates a deliberate action, the frontal lobe is centrally involved.