Novel anti-IL-23p40 specific human Ig derived proteins, including, withoutlimitation, antibodies, fusion proteins, and mimetibodies, isolated nucleicacids that encode the anti-IL-23p40 Ig derived proteins, vectors, host cells,transgenic animals or plants, and methods of making and using thereof, areuseful for therapeutic compositions, methods and devices. Preferably, the anti-IL-23p40 specific human Ig derived proteins do not bind the p40 subunit of IL-12 and, thus, do not neutralize IL-12-related activity.