Upstream from the Earth's quasi-parallel bow shock, the Lockheed Plasma Composition Experiment on ISEE 1 often observes two types of suprathermal He2+ distributions. Always present to some degree is an energetic (several keV/e to 17.4 ke V/e, the maximum energy of the detector) ''diffuse'' He2+ distribution. Sometimes, apparently when the Alfven Mach number, MA, is high enough and the spacecraft is near the shock (within a few minutes of a crossing), a second type of suprathermal He2+ distribution is also observed. This nongyrotropic, gyrating He2+ distribution has velocity components parallel and perpendicular to the magnetic field that are consistent with near-specular reflection of a portion of the incident solar wind He2+ distribution off the shock. Specularly reflected and diffuse proton distributions are associated with these gyrating He2+ distributions. The presence of these gyrating He2+ distributions suggests that specular reflection is controlled primarily by magnetic forces in high Mach number quasi-parallel shocks and that these distributions may be a seed population for more energetic diffuse He2+ distributions. ¿ American Geophysical Union 1990