This paper attempts to determine the best way to maximize the contribution of agriculture to the growth and global modernization of Africa. By using middle-income African countries as a sample, this paper studies the effect of industrialization, human capital, economic opening and institutional quality on the value added by the agricultural sector. The quality of human capital exerts an accelerating effect of the agricultural value added. Indeed, the level of human capital determines the ability to use a technology or innovation capacity. The results require the establishment of appropriate institutional arrangements to overcome the constraints that agricultural products face in market and to turn capital and investment towards agriculture.