We review the recent evidence that distinguishes particles accelerated in flares and in shock waves driven by coronal mass ejections (CMEs). CME‐driven shocks, not flares, produce most of the large particle events at 1 AU and can accelerate protons up to 20 GeV. In contrast, flare‐accelerated ions have characteristic abundances produced by resonant wave‐particle interactions in the flare plasma. Only the direct particle observations have allowed us to study this new physics of ion acceleration in flares, since the energetic ion abundances have been largely invisible in photons. ©1996 American Institute of Physics.