This book highlights current approaches and future trends in the use of mass spectrometry to characterize protein therapies. As one of the most frequently utilized analytical techniques in pharmaceutical research and development, mass spectrometry has been widely used in the characterization of protein therapeutics due to its analytical sensitivity, selectivity, and specificity. This book begins with an overview of mass spectrometry techniques as related to the analysis of protein therapeutics, structural identification strategies, quantitative approaches, followed by studies involving characterization of process related protein drug impurities/degradants, metabolites, higher order structures of protein therapeutics. Both general practitioners in pharmaceutical research and specialists in analytical sciences will benefit from this book that details step-by-step approaches and new strategies to solve challenging problems related to protein therapeutics research and development.