LGS

LGS may refer to:


 * Lanark Grammar School
 * Larne Grammar School
 * Liselere Geçiş Sınavı, the old name for OKS.
 * Lahore Grammar School
 * Langley Grammar School
 * Leeds Grammar School
 * Leicester Grammar School
 * Looking Glass Studios, a defunct computer game company
 * Loughborough Grammar School, one of the Loughborough Endowed Schools
 * Laser guide star, an adaptive optics instrument used in Astronomy