Evidence exists suggesting that not only do heliospheric shocks accelerate particles up to energies as high as a few GeV/nuc. but that the source of these energetic particles are pickup ions or low energy particles present in the suprathermal tail of the solar wind distribution. To be diffusively accelerated at a shock wave a particle needs an energy significantly greater than that of the expected source particles, the so-called injection problem. We present here a model of particle acceleration at shocks of arbitrary obliquity that produces particle energies sufficiently high for diffusive shock acceleration to occur. ¿ 2000 American Geophysical Union