Exoplanet observations have revealed numerous examples of systems hosting planets residing in mean motion resonances. These dynamical configurations are usually assumed to be the product of past orbital migration due to interactions with a proto-planetary disk. Planets that experience smooth migration and eccentricity-damping forces due to a protoplanetary disk should not only be captured into mean motion resonances but also end up in specific dynamical configurations within these resonances. I will describe a method to fit exoplanet observations in order to test whether planetary systems reside in these special configurations and show how the results of these fits can be used to draw conclusions about the migration histories of resonant planets. These results provide empirical constraints that can inform theories of planet-disk interactions.