The design and implementation of a nondestructive method for evaluating interlaminar bonding during the in-situ thermoplastic tow placement process was developed. This method utilizes two piezoelectric transducers in a "pitch-catch" arrangement. Each transducer is mounted on an acrylic wedge which, in turn, is mounted on a steel mediator wedge. This "double wedge" assembly produces Rayleigh surface waves in a composite specimen without a gel couplant. The received signals are analyzed for changes in the Rayleigh wave speed. Poorly bonded top most plies cause the Rayleigh wave velocity to decrease by as much as 30%. Verification of this bond quality sensor is demonstrated under various tape laying conditions. In each specimen, the Rayleigh wave velocity was measured. The bond quality was assessed quantitatively with a peel test and qualitatively by visual inspection (photomicrographs). The Rayleigh wave velocity was compared with the strength and thickness of the bond between the top ply and substrate. The Rayleigh wave speed increases linearly with the top ply peel strength. Photomicrographs indicated that poorly bonded specimens have a resin rich region at the top ply/substrate interface. These tests demonstrate that the double wedge sensor can measure bond quality during in-situ consolidation of thermoplastic matrix composites.