Abstract: A utility knife includes a folding handle in which a neck folds into a handle base. A neck lock locks the neck in its closed or open position relative to the handle base. The neck is spring-biased toward its open position to assist in one-handed opening of the handle. A utility blade and blade holder are slidably carried by neck for manual movement between retracted/protected and extended/exposed positions. The neck cannot be folded into or locked in the closed position if the blade is exposed.