Electrospray ionization mass spectrometry (ESI-MS) has revolutionized the study of a vast array of compounds previously inaccessible to gas-phase analysis. Electrospray is a soft ionization technique that causes little orno fragmentation of a sample. This is ideal for simple mass analysis and isotope matching of low M w compounds, but also allows the accurate mass determination of high mass molecules (e.g. proteins) from m/z data of each of the charge states of the molecular ion. Minimizing fragmentation also simplifies the interpretation of mixtures, which may otherwise be impossible with the presence of fragment ions. Collision-induced dissociation (CID) in an ESI source (MS) or collision cell (MS/MS) can be used to impart energy to the ions, leading to the formation of fragment ions. Voltages in the source or collision cell can be ramped to control the level of fragmentation, providing useful structural information. However, this produces a vast quantity of data, which can prove unwieldy to handle, interpret, and present. Energy-dependent electrospray ionization mass spectrometry (EDESI-MS) provides a simple and effective solution by presenting the information acquired by CID at all voltages in a compact, 2D format.