Abstract: A sliding knife with disengaging blade actuation mechanism comprises: a hollow handle; a blade having a detent near its base end and slidable within the handle between a first, fully retracted position and a second, deployed position; and a disengaging blade actuation mechanism, called a “tongue,” which fits over the blade and within the handle, and has a ball dimensioned to fit within the blade's detent. In a retracted position, the blade and tongue lie within the handle. To extend the blade, the tongue is pulled away from the handle, pulling the blade along with it. Then, once the blade is fully extended, the tongue disengages from the blade. Thus, the tongue can be attached to clothing, and the knife can be actuated by simply pulling down on the handle with one hand. The knife also has locking mechanisms for securing the blade in its deployed and retracted positions.