Photoresponse measurements were made to determine the compositional dependence of the Ga1−xAlxAs direct &Ggr;15→&Ggr;1and indirect &Ggr;15→X1energy gaps. These data, together with other information, show that the crossover composition and energy gap are between 0.35<xc<0.40 and 1.87<Egc<1.97 eV, and that the most resonable values are 0.37 and 1.92 eV.