In this talk I discuss aspects of an accelerating universe, both early universe inflation and late time acceleration, within the framework of effective field theory. I begin by reviewing the Weinberg argument showing that the equivalence principle of general relativity derives from the theory of massless spin 2 particles at large distances, and I review how an accelerated phase of inflation arises from this effective theory of spin 2 particles plus spin 0 particles with special interactions. I discuss attempts to embed such an effective theory into string theory and conformal gravity. I then discuss theoretical problems, such as infinities and causality violation, in alternate effective theories of acceleration from modifying gravity. Finally, I build an effective theory of large scale structure, whose details are sensitive to late time acceleration, and mention connections to reheating and particle physics.