Atom interferometers have been used to perform precise gravitational measurements. In this talk, I will review atom-interferometric equivalence principle tests, measurements of spacetime curvature, and the observation of a gravitational Aharonov-Bohm effect. I will discuss current efforts to detect gravitational waves and to search for dark matter with atom interferometry. Finally, I will describe the design of an experiment to demonstrate matter-wave interferometry with microparticles containing up to 10^13 atoms.