The folding knife of the present invention includes a handle having first and second handle members that are maintained in spaced, parallel relation to one another by spacing elements that define a groove therebetween. The blade is pivotally attached to the handle at its tang portion and is movable into and out of the groove between its fully open and fully closed positions. A coil spring, or equivalent, may be interconnected between the tang and handle to provide an assisted opening mechanism. A blade lock includes a user actuated button that passes through an elongated slot formed through one of the handle members and through a circular opening formed through a bias plate that is positioned within the handle, and a plunger element that is spring biased in a direction transverse to the longitudinal axis of the blade.