This paper examines the application of through-transmission ultrasonic (TTU) Acoustography NDE to detect and quantify the kissing bond and weak bond defects in adhesively bonded CFRP-Aluminum (CFRP-Al) lap joints. The bondline defects in CFRP-Al lap joint coupons were simulated by introducing silicone lubricant, aircraft hydraulic oil, and poly-vinyl alcohol (PVA) on the bonding surface of composite substrate. Similarly, the weak bond samples were fabricated by altering the resin-to-hardener ratios (A/B). The TTU Acoustography method, operating at 3.8 MHz, was able to detect the surface contaminant in the bondline and was also able to show some differences in the TTU Acoustography images for the weak bond samples. The correlation of lap shear test data with Acoustography ultrasonic attenuation was also carried out for the quantitative evaluation of failure load in composite joints.