The generation of dynamic models of biological processes critically depends on the determination of precise cellular concentrations of biomolecules. Here we report the cellular concentration for most expressed E. coli proteins reflecting 55% of the predicted genes (>2000 proteins) assessed under 22 different experimental conditions. The data were generated by combining efficient sample fractionation and state of the art quantitative mass spectrometry and represent the most comprehensive, condition-dependent protein abundance map for any organism to date. These data allowed us, for the first time, to define system-wide protein relationships between cell growth and protein expression across different conditions, defining proteome dynamics at different levels including functional, localization and posttranslational adaptations. We envision that the generated comprehensive quantitative E. coli proteome data, together with the identified protein modifications will become a major resource for the systems biology community and a great source for new discoveries of the broader E. coli community.