A folding knife with a locking mechanism, and a method of assembly of the locking mechanism are disclosed. In one embodiment, the locking mechanism is formed from a second locking element slidably mounted on the blade to engage at least part of a first locking element on the handle and lock the blade in the open position. The second locking element and blade may be configured to allow simple, one-handed locking and unlocking of the blade with a single thumb-actuated motion. The second locking element also may be configured to allow one-handed opening and/or closing of the blade.