A belt system convertible into and out of a sit harness configuration for selective use as a harness or a utility belt features a pair of leg loops and a waistband equipped with a quick release buckle. Support straps projecting from the leg loops are arranged for releasable engagement to the waistband and releasable engagement to one another so that the releasable engagement to one another when also engaged to the waistband provides a second closure thereof so that the waistband remains closed by the connection between the support straps even if the quick release buckle on the waistband is inadvertently disengaged. Using only a single waistband, the belt system provides a quick release function when used only as a utility belt, yet avoids the hazard of having the waistband open by inadvertent release of the quick release waistband buckle during use as a harness.