It is proved that the energy exchange processes during the laminar boundary layer transition into turbulence in the presence of free stream turbulence , take place in accordance with the relationships that govern the same energy exchange processes of the phenonenon in the case of a quiescent free stream. Bradshaw's method (Bradshaw et al, 1974) for calculating the turbulent boundary layer, succeeded in predicting with a reasonable accuracy, the development of the two-dimensional boundary layer during the final stages of transition and before the turbulent boundary layer is fully developed, without introducing any changes in the original program to account either for the turbulence in free stream or for the fact that the boundary layer is not fully developed. These changes will be delt with in future work. This implies that, the development of the turbulent quantities within the transitional-turbulent boundary layer follows the universal turbulent boundary layer mechanisms regardless of the level of the free stream turbulence. It is also an indication of the validity of Abdel-Kareem (197e) conclusion that the mechanism of the laminar boundary layer transition is ,universal regardless of the free stream turbulence level .