Ithaca Stringed Instruments (ISI) is a small custom shop based in the Finger Lakes region of upstate New York, building handcrafted guitars, violins, mandolins, and amplified-acoustic pickups. The shop traces back to luthier Eric Aceto, who began building at The Ithaca Guitar Works in 1989 and split off with D.S. Hoffman to form ISI in 1995. The operation now runs out of Trumansburg, NY, with Aceto and his son Jordan producing roughly ten instruments a year.

The shop is best known for blending traditional American lutherie with modern amplified performance. Flagship guitar lines include the Oneida acoustic-electric, which pairs aged spruce or cedar tops with maple, mahogany, koa, rosewood, or walnut backs over a radial-braced body and graphite-reinforced mahogany neck, and the Parlor, a 12-fret small-body design offered in spruce-topped configurations with rosewood, acacia, or maple back and sides. ISI also builds the NV line of amplified violins and the Aceto/Violect Deluxe Pickup System, a twin-sensor transducer used by acoustic and electric string players for live work.

ISI's amplified violins and pickup systems have been used by jazz violinist Jean-Luc Ponty, fiddler Darol Anger, and violinist Zack Brock. Tommy Malone of The Subdudes is among the guitarists associated with the shop's instruments.

Ithaca Stringed Instruments has 3 products cataloged on Equipboard, including Parts and Violins. Their gear is featured by 1 artist, with the strongest followings in Funk / Soul and Jazz. Notable users include Zach Brock.