A method and apparatus for enabling the speculative forking of a speculative thread is disclosed. In one embodiment, a speculative fork instruction is conditioned by the results of a fork predictor. The fork predictor may issue predictions as to whether or not a speculative thread would execute desirably. The fork predictor may be implemented as a modified branch predictor circuit, and may have execution history updates entered by a determination of whether or not the execution of a speculative thread was or would have been desirable.