This volume consists of eighteen peer-reviewed papers related to lectures on pseudo-differential operators presented at the meeting of the ISAAC Group in Pseudo-Differential Operators (IGPDO) held at Imperial College London on July 13-18, 2009. Featured in this volume are the analysis, applications and computations of pseudo-differential operators in mathematics, physics and signal analysis. This volume is a useful complement to the volumes “Advances in Pseudo-Differential Operators�, “Pseudo-Differential Operators and Related Topics�, “Modern Trends in Pseudo-Differential Operators�, “New Developments in Pseudo-Differential Operators� and “Pseudo-Differential Operators: Complex Analysis and Partial Differential Equations� published in the same series in, respectively, 2004, 2006, 2007, 2009 and 2010.