A knock-down portable partition system has cover panels supported on a post and beam framework designed for quick and easy on-site manual assembly. The framework includes at least two vertical posts and at least two structural beams rigidly, yet detachably interconnecting the vertical posts. Connectors secure the beams to the posts, such that the partition system can be assembled and disassembled manually. The partition system may include utility troughs shaped to retain wires, cabling, etc. therein to provide power and/or communication to the system. The utility troughs have opposite ends shaped to be detachably mounted to the posts.