Embodiments of techniques and technologies to verify the interference fit of fasteners are disclosed. In one embodiment, a transducer is positioned to transmit a shear ultrasonic signal through a region of a fastener which is subject to stress when the fastener experiences an interference fit. The shear ultrasonic signal is transmitted through a region of the fastener subject to the stress. As the transmitted ultrasonic signal encounters the region, it is mode converted corresponding to a degree of interference which the fastener is experiencing. A return ultrasonic signal from the fastener is received with the transducer. From the return ultrasonic signal, a processor determines the degree of interference fit which the fastener is experience and outputs an indication of the same.