Spin-label electron spin resonance (ESR) has emerged as a powerful tool to characterize protein dynamics. One recent advance is the development of ESR for resolving dynamical components that occur or coexist during a biological process. It has been applied to study the complex structural and dynamical aspects of membranes and proteins, such as conformational changes in protein during translocation from cytosol to membrane, conformational exchange between equilibria in response to protein-protein and protein-ligand interactions in either soluble or membrane environments, protein oligomerization, and temperature- or hydration-dependent protein dynamics. As these topics are challenging but urgent for understanding the function of a protein on the molecular level, the newly developed ESR methods to capture individual dynamical components, even in low-populated states, have become a great complement to other existing biophysical tools.