Mesa/Boogie (also known as Mesa Engineering) is an American company in Petaluma, California that manufactures amplifiers for guitars and basses. It has been in operation since 1971.

MESA was started by Randall Smith as a small repair shop which modified Fender Amplifiers, particularly the diminutive Fender Princeton. Smith's modifications gave the small amps much more input gain, making them much louder as well as creating a high-gain, distorted guitar tone. Prominent early customers included Carlos Santana, and Ron Wood and Keith Richards of The Rolling Stones. Exposure from these top players helped to establish Mesa/Boogie's position on the market, and it is frequently referred to as the first manufacturer of boutique amplifiers.[