A capo for a stringed instrument includes a first jaw member and a second jaw member with respective first and second jaw surfaces. A tightening mechanism is disposed on the first jaw mechanism, and is adapted to place a lateral member in tension between the first and second jaw members. The tension on the lateral member urges the first and second jaw members of the capo inward towards a neck of a stringed instrument, such that the capo is removably but stably supported by the neck of the instrument. The lateral member is disposed in spaced relation above a fingerboard of the instrument. The lateral member supports one or more string contacting members that serve to adjustably urge respective instrument strings toward the fingerboard, thereby changing the tuning of the instrument. Friction between the first and second jaw surfaces and the neck of the instrument serves to oppose a force between the string contacting member and the string, such that the string may be urged towards the fingerboard without a further member traversing a rear surface of the instrument neck.