The lateral septum (LS) is located between the corpus callosum and medial septum (MS) and predominantly composed of γ‑aminobutyric acid‑ergic neurons. The LS, a nexus of the limbic system, integrates hippocampus inputs, and projects abundant output connections to the hypothalamus to regulate variety of functions, including emotional, social, and motivational behavior. Emerging evidence suggests the neuroanatomical and functional heterogeneity of the LS. This article overviews diverse neuron subtypes and the regulatory effects of their neural circuit on anxiety, fear, movement, aggression, feeding, memory, sleep, and anesthesia. These mechanisms will provide reference for further understanding physiological and pathophysiological effects of the LS.