The frontal lobe is one of the four major lobes of the cerebral cortex of the human brain. It is the largest part of the human brain and is positioned immediately behind the forehead. It is the part of the brain thought to have expanded the most during human evolution. The frontal lobe serves as the conductor of higher order thinking: It regulates and mediates reasoning and execution of behaviors via extensive neural networks. Damage to the frontal lobes can result in significant impairment in higher order reasoning, behavioral regulation, and decision making. This entry discusses the structure, function, and various disorders of the frontal lobe.