On the cutting edge of medical diagnostics, plasma proteomics promises to generate a new wave of technologies to help identify many different diseases and disease risks. Plasma and serum are the preferred non-invasive specimens to test normal individuals, at-risk groups, and patients for protein biomarkers discovered and validated to reflect physiological, pathological, and pharmacological phenotypes. These specimens present enormous challenges due to extreme complexity, huge dynamic range in protein concentrations, non-standardized methods of sample processing, and intra- and inter-individual variation from genetics, diet, smoking, hormones, and other sources. This book presents the major findings from the collaborative Plasma Proteome Project organized by the international Human Proteome Organization (HUPO). The chapters are drawn from a larger set of publications in the journal PROTEOMICS. This book provides a valuable foundation for development and applications of proteomics.