The small, high-pitched guitar-like instrument used in mariachi music is the Mexican vihuela.
The Mexican vihuela is a compact plucked string instrument with five strings and a rounded, arched back. It supplies rhythmic harmony and a bright, projecting sound in mariachi ensembles. Players often strum it with force, helping create the energetic rhythmic foundation associated with the style.
Although its name is shared with historical Spanish vihuelas, the Mexican instrument is a distinct later development. The older Spanish vihuela was a Renaissance fretted instrument that resembled a guitar and was commonly played in courtly music. The Mexican vihuela became established in mariachi instrumentation alongside the guitarrón, guitar, violins, and trumpets.
Its tuning is re-entrant, meaning the strings are not arranged in a simple low-to-high sequence. The vihuela is therefore not merely a small classical guitar; its body shape, tuning, and forceful strumming serve a specialized ensemble role.