A trapeze conduit support system includes a support bracket, and a moveable retention member, which are configured to be suspended from and carried by a pair of vertically extending support members, such as for mounting of conduits at or near a ceiling, beam, or like supporting structure of an installation. The retention member is moveable between a first, open position, wherein the conduits can be “laid in” to the support bracket, and a second, closed position wherein the retention member retains the conduits in position within the support bracket. Convenient and efficient installation of conduits is thus facilitated.