Abstract: A sofa bed mechanism consisting of three sections, namely, a rear section, an intermediate section, and a front section, that are foldable between collapsed sofa positions in which the sections are in substantially horizontal vertically stacked positions and bed positions in which the sections extend in substantially horizontal alignment. A frame supports the sections, the frame being of minimum width by which is meant the frame is of a shallow dimension in a direction front to rear of the sofa. The sections are stacked on top of the frame in their sofa positions so that the frame and the sections present a compact substantially rectangular profile when viewed from the end of the frame, thereby allowing substantial flexibility in the design of the sofa in which the mechanism is mounted. The end sections are connected by hinge assemblies located entirely on the sides of the assemblies to avoid the necessity for any cross tubes that might interfere with sleeper comfort in the bed position of the mechanism.