Large wind turbines are very complex machines that are not able to work without control. On the other hand, a wind turbine is a system, whose interacting subsystems are characterized by a strong interdisciplinarity. Thus, the control of such systems has to be organized in different hierarchic control levels and satisfy control objectives of diverse nature. For this end, the corresponding control strategies have to be integrated in a unique concept and the control objectives of each control layer, which are often contradictory, must be conciliated such that the machine is able to work in the best conditions. This chapter is devoted to describe in general the hierarchic control system, the multi-sided control objectives and the associated strategies.