A folding knife having a blade and integral tang pivotally mounted to a handle with a cantilever spring fixedly attached at one end to the handle and extending to a free, terminal end having a lobed portion. A camming member fixed to the tang has a camming surface spaced from the pivot axis extending through the tang. The lobed portion of the spring contacts the camming surface when the blade is in the fully closed position and remains in contact throughout a first portion of the blade movement toward the open position. The spring is out of contact with the camming surface during a second portion of blade movement, from the end of the first portion to the fully open position. Momentum developed by spring force applied to the camming member during the first portion of blade movement is sufficient to move the blade through the second portion of its movement to the fully open position. Cooperative stop portions on the tang and handle define the limits of blade movement to fully open and closed positions, and resiliently lock the blade in the fully open position.