This project aims at studying how recent interactive and interaction technologies would help extend how we play the guitar, thus defining the “multimodal guitar”. We investigate two axes, 1) “A gesturalpolyphonic sensingprocessing toolbox to augment guitar performances”, and 2) “An interactive guitar score following environment for adaptive learning”. These approaches share quite similar technological challenges (sensing, analysis, processing, synthesis and interaction methods) and dissemination intentions (community-based, low-cost, open-source whenever possible), while leading to different applications (respectively artistic and educational), still targeted towards experienced players and beginners.