The article provides a comprehensive tutorial on Selected Reaction Monitoring (SRM) for quantitative proteomics. SRM, also known as Multiple Reaction Monitoring, is a technology that enhances the reliability of quantifying low-abundance analytes in complex mixtures, complementing the shotgun approach in systems biology. The tutorial covers the selection of proteotypic peptides, optimization and validation of transitions, and factors affecting sensitivity and accuracy. It emphasizes the importance of specific m/z settings for precursor and fragment ions to achieve high selectivity and sensitivity. The article also discusses the validation of transitions through MS/MS spectra and the use of heavy isotope-labeled peptides. Additionally, it addresses the design of SRM assays, including the trade-offs between dwell time and cycle time, and the importance of normalization for accurate quantification. The tutorial concludes with a discussion on absolute quantification using isotopically labeled internal standards.The article provides a comprehensive tutorial on Selected Reaction Monitoring (SRM) for quantitative proteomics. SRM, also known as Multiple Reaction Monitoring, is a technology that enhances the reliability of quantifying low-abundance analytes in complex mixtures, complementing the shotgun approach in systems biology. The tutorial covers the selection of proteotypic peptides, optimization and validation of transitions, and factors affecting sensitivity and accuracy. It emphasizes the importance of specific m/z settings for precursor and fragment ions to achieve high selectivity and sensitivity. The article also discusses the validation of transitions through MS/MS spectra and the use of heavy isotope-labeled peptides. Additionally, it addresses the design of SRM assays, including the trade-offs between dwell time and cycle time, and the importance of normalization for accurate quantification. The tutorial concludes with a discussion on absolute quantification using isotopically labeled internal standards.