Caution! REBOL currently doesn't deep copy derived objects with embedded objects in them. Your best bet is: obj!: [a: "" b: ""] obj: make object! obj! t!: append copy/deep obj! [c: ""] t: make object! t! Extend: func [Base [block!] Extension [block!]] [ append copy/deep Base Extension ] r!: Extend t! [d: ""] r: make object! r! Andrew Martin ICQ: 26227169 http://members.xoom.com/AndrewMartin/ -><-