Sensor location selection for structures is demonstrated via identifiability analysis. The sensitivities of sensor outputs to structural stiffness coefficients are computed by a model and transformed via continuous wavelet transforms into the time-scale domain to characterize their shape attributes and accentuate their differences. Regions are then sought in the time-scale plane wherein the wavelet coefficient of an output sensitivity surpasses all the others’ as indication of the sensitivity's uniqueness. This yields a comprehensive account of identifiability by each output for individual stiffness coefficients as the basis for output selection. The proposed output selection strategy is demonstrated for an eight-story building frame model.