The successful soybean intercropping system with maize requires choosing tolerant soybean varieties to shading stress under intercropping, as well as appropriate plant population densities and distribution within the intercropping system. High competition between the two intercrops for essential growth resources may exist when incompatible soybean variety with the wrong plant density was chosen. In this chapter, we assessed the contribution of land equivalent ratio (LER) in defining the compatibility and competition in the intercropping system of soybean and maize. Furthermore, the role of system production index (SPI) in distinguishing between complementary and complimentary in the intercropping system of soybean and maize was also tackled. Lastly, the ability of five studied soybean varieties to tolerate shading stress under its intercropping system with maize was thoroughly discussed through previous research conducted in Egypt.