Quadrupole Resonance (QR) has recently been shown to be a feasible method for the non-contact measurement of strain in polymeric fiberglass-reinforced composites. Tiny crystals of a QR active additive are embedded into the composite or are applied as part of a surface coating. Strains in the composite are transferred to the additive crystals. These crystals can be interrogated via radio frequency pulses provided by a single-sided radio frequency coil. Thus, the additive crystals give rise to a strain dependent QR frequency response. The QR frequency and line width from composites containing additive are found to be sensitive parameters for the measurement of tensile strain. The QR active additive that was embedded in the composite matrix was found to be inert and non-intrusive.