Abstract: A portable stair-ladder platform comprising a adder support platform (1) and a support member (3,21,41,59,75,85) pivotally attached to the platform by a pivotal coupling (9,84,86), the parts being arranged such that, when assembled and in use with the ladder support platform substantially horizontal and the support member substantially vertical, an upwardly-facing surface area of the support member abuts a downwardly-facing surface area of the ladder support platform, the pivotal coupling and the surface areas being arranged to tend to maintain substantially a right angle between the abutting parts even when weight is applied to the ladder support platform, and the pivotal coupling being such as to prevent pivoting of the support member substantially beyond the vertical in that angular direction which is towards the underside of the ladder support platform but while allowing pivoting of the support member in the other direction so as to allow the device to be collapsed for transportation or storage.