This chapter discusses the challenges and the possibilities offered by controlling a data center as a node of the smart-grid. The communication between the grid and the data center takes the form of a time-varying and power-consumption-dependent electricity price. A model that considers both the computational and the physical characteristics of a data center, as well as their interactions, is proposed. Two control approaches are discussed. The first control approach does not consider the interaction between the computational and the thermal characteristics of a data center. We call such a control approach uncoordinated. The second controller considers the coupling between the computational and the thermal characteristics. We call such a control approach coordinated. Simulation results, discussed at the end of the chapter, show that the coordinated control approach can lead to larger income for data center operators than the uncoordinated approach.