Abstract: A ladder leg support apparatus includes a support member having upstanding inner side and back walls and inclined outer side and back walls. Flanges selectively positioned along the inner side walls support a plate at a selected height for supporting a ladder leg thereon. An auxiliary side panel is pivotally coupled to an outer side wall and may be extended and supported with a support leg to provide stability when the support member is positioned on a stair. The apparatus further includes a platform having a support surface on which the support member may be positioned. The platform includes threaded leg assemblies which may be extended to a downwardly adjacent stair to support the platform on a selected stair. The platform includes at least one sight level for verifying the proper support leg length adjustment.