Surface deformation resulting from anthropic activities or crustal motion is a major concern for land use planning and engineering risk assessment. Spaceborne interferometric synthetic aperture radar (InSAR) has evolved in the past decades as a unique tool for quantitative measurements of regional deformation with large coverage and a high accuracy of centimeters to millimeters. To mitigate the technical limitations of InSAR, persistent scatterer InSAR (PSI) techniques have been proposed in recent years to extract deformation signals from a set of interferograms and to estimate the atmospheric phase screen and digital elevation model (DEM) errors. In this chapter, we rst review the basic concepts and principles related to PSI. We then present the mathematical models and the data reduction procedures of the PSI methodologies that have been developed by our research group for regional deformation detection. The experimental results derived by the two approaches using the European Remote Sensing (ERS)-1/2 SAR imagery are also reported for mapping spatiotemporal deformation over the two study areas: Phoenix, Arizona, and the Los Angeles basin, California, in the United States.