For several decades polymer field theory has been an important computational and theoretical tool for predicting and interpreting the phase behavior of polymers. Many emerging applications of polymer materials involve blending polymers with nanoparticles to improve performance; however, the thermodynamics of these systems remains relatively poorly understood. In this chapter, we summarize numerous recent advances in polymer field theory with a focus on our approach to extend polymer field theory to describe polymer nanocomposites. We discuss recent applications of the methods as well as the mutual advantages and disadvantages of various implementations and conclude with a discussion of the challenges and ongoing development of the methods.