A difference contact network analysis (dCNA) method is developed for delineating allosteric mechanisms in proteins. The new method addresses limitations of conventional network analysis methods and is particularly suitable for allosteric systems undergoing large-amplitude conformational changes during function. Tests show that dCNA works well for proteins of varying sizes and functions. The design of dCNA is general enough to facilitate analyses of diverse dynamic data generated by molecular dynamics, crystallography, or nuclear magnetic resonance.