The band gap of Ga0.52In0.48P varies considerably, depending on conditions of growth. This is a result of ordering in the CuPt structure. Details of the ordering also lead to more subtle optical effects. We report here on photoluminescence (PL) and photoluminescence excitation (PLE) measurements on ordered and disordered Ga0.52In0.48P. The dominant high energy emission process in disordered GaInP has been established to be excitonic, but the exciton trapping energy is not unique. PLE from ordered Ga0.52In0.48P shows significant tailing of electronic states and a ‘‘band edge’’ which depends on detection energy.