In this dissertation, I present a method for improving the accuracy of Interferometric Synthetic Aperture Radar (InSAR) measurements of crustal deformation by reducing the impact of atmospheric propagation delays on the radar phase. The proposed technique (CANDIS) is based on the idea of common scene stacking, which takes advantage of the fact that interferograms that share a common scene also share the same atmospheric contribution. I show that this new technique can be used to study a variety of crustal motions that could not be observed otherwise. The first chapter is an introduction and a summary of the dissertation. The second chapter provides a detailed description of the new method and its validation. Also in the second chapter we apply the new atmospheric correction to several study areas in the Eastern California Shear Zone. The third chapter combines InSAR and Global Positioning System (GPS) data to study strain accumulation on the San Jacinto fault, and locate a previously unrecognized buried fault trace. The fourth chapter is a study of time-dependent crustal deformation due to volcanic activity in South America. In the final chapter, I show an application of the CANDIS method to the study of episodic creep on the San Andreas fault.