Proteins represent the most diverse molecules of living organisms and play a central role in virtually all biological structures and processes. Therefore, methods for the isolation and characterization of proteins are the foundation of any cell and molecular biology research. All the standard methods presented have been successfully used at the German Cancer Research Center in Heidelberg for a long time and are continuously optimized. Thanks to numerous practical tips and an additional appendix with safety regulations, a directory of sources, and recipes for standard solutions, the detailed protocols can be easily understood even without years of laboratory experience.