We present a cross-calibration of Fermi LAT and AGILE-GRID. Using analysis of simultaneous observations at both very long and very short time scales of gamma-ray pulsars including Vela and B1509-58, we compare the light curves, fluxes, and spectra obtained by the two instruments. We pay particular attention to the effects at low energies of both energy dispersion and the steep change in effective area as a function of energy.