A Collapsible Trailer. The trailer is lightweight, but durable, and includes a set of detachable deck segments that can be assembled into a deck. The trailer further includes a suspension assembly that attaches to the deck once the deck is assembled or, alternatively, is permanently attached to one deck segment. Intra-deck segment support is provided by slidable rods that are extendable to bridge between a pair of adjacent segments. Each deck segment has a male edge to be inserted into a female edge to create an exceedingly strong, interlocking hinge-like structure. The deck and trailer can be assembled without the need for any tools. The deck segments, when disassembled, are stackable into a condensed deck stack. A foldable suspension facilitates the stackable storage and transportation of the trailer. The trailer is convertible into a cargo platform that can be attached directly to a conventional trailer hitch receiver on a vehicle.