The choice of perturbation inputs is critical in the identification and model building exercise. Accurate identification requires that the input be persistently exciting so as to excite all modes or frequencies of interest. However, there are multiple objectives that need to be considered. Multi-harmonic signals are a convenient choice for frequency domain identification. Multi-objective optimization formulations for synthesis of multiharmonic signals are presented. Copyright © IFAC Dynamics and Control of Process Systems, Cambridge, Massachusetts, USA, 2004