Quark Model Calculations of the N to Delta Reaction

The electromagnetic excitation of the nucleon resonances is studied in the framework of Constituent Quark Models. Particular attention is devoted to the transition to the $\Delta$ resonance and to the issue of a possible deformation of hadronic systems, mainly in connection with the problem of the quadrupole excitation. The analysis of the emerging discrepancies between data and theoretical predictions is discussed and shown to lead to important conclusions concerning the internal dynamical structure of hadrons.