Among the proposals for the dark energy --- which comprises ~2/3 of the energy density of the Universe and is responsible for the accelerating cosmic expansion --- is a dynamical, inhomogeneous, negative pressure field, or quintessence. Quintessence dark energy predicts a different expansion history than a cosmological constant, a feature which has been exploited to design future tests to distinguish various dark energy proposals. Another distinguishing feature is the inhomogeneity or lumpiness. That is, a dynamical field must clump (or anti-clump) in response to a gravitational field, whereas a cosmological constant does not. In this talk I will discuss various methods to observe the clumping of a quintessence field, and explain how such observations can reveal information about the microphysics behind the dark energy.