A restraining system and method for detachably securing a ladder to a shoring or excavation support structure. The restraining assembly, primarily configured from an elongated flexible restraining material, includes a proximal member, possessing a fastener configured to removably attach onto either side rail of a ladder. The assembly further includes a distal member, possessing a fastener configured to removably attach to a shoring anchor located on the top portion of a shoring wall. The mediate portion of the restraining assembly is configured to concurrently retain both the proximal and distal members, including a tensioning means for the adjustment of the overall functional length of the restraining assembly. In particular embodiments, the restraining system includes a shoring or excavation support structure having at least one shoring wall that includes a multiplicity of shoring anchors attached at predetermined locations.