This work provides and highlights the effects of microscopic ordering on the properties of semiconductor alloys. It brings us one?step closer in understanding the fundamental ground that influences the properties of semiconductor alloys. For the alloy studied, i.e. AlGaAs, GaInP, BGaP, and AlGaInP, our results can serve as a guide for theoreticians, experimentalists, and device engineers to focus on the microscopic structures that are predicted to give their desired properties. This work will draw attentions to the fact that properties of semiconductor alloys can be adjusted by controlling the atomic ordering in addition to the alloy composition. This opens up a new way to control semiconductor properties, such as bandgap and electron effective mass. This work also helps to gain better understanding in the relationship between atomic arrangements in alloys and the observable properties.