Mass spectrometry (MS) offers unmatched capabilities for the detection, characterization, and identification of a broad range of analytes. Mass spectrometry imaging (MSI) integrates MS data with information on the spatial distributions of the analytes, further enhancing the applicability of MS. In Mass Spectrometry Imaging: Principles and Protocols, expert practitioners from academia, industry, and the clinic contribute cutting-edge protocols describing the application of MSI to investigations of analyte localization in a variety of specimens, from microorganisms to plant and animal tissues. Divided into three sections, this volume presents the principles of MS, current and future trends of MSI, and qualitative and quantitative protocols to measure and identify endogenous metabolites and xenobiotics. An array of MSI approaches and technologies for characterizing peptide and protein distributions are described in detail. Written in the highly successful Methods in Molecular Biology™ series format, protocol chapters include introductions to their respective topics, lists of the necessary materials and reagents, and step-by-step, readily reproducible laboratory procedures. Also included are notes providing tips to avoid experimental pitfalls and helpful suggestions for method troubleshooting. Comprehensive and up-to-date, Mass Spectrometry Imaging: Principles and Protocols is written for scientists, biological and chemical engineers, and clinicians who are interested in applying MSI in their work and those who would benefit from having detailed experimental guidelines available in a single, convenient source.