A study of the structural stability of boron nanoribbons is presented. Antiaromatic instabilities are found to destabilize boron nanoribbons. Our studies suggest that nanoribbons obtained from "α sheets" are more stable than those from reconstructed {1221} sheets and traditional triangular boron sheets. The stability of the nanoribbons increases with an increasing ribbon width resulting in an increased hole density (η) and, hence, an increased number of hexagonal motifs in the nanoribbon. The boron nanoribbons formed are mostly metallic; however, semiconducting structures have also been observed.