The modified tilted sandwich debond (TSD) test method is used to examine face/core debond fracture toughness of sandwich specimens with glass/polyester face sheets and PVC H45 and H100 foam cores over a large range of mode-mixities. The modification was achieved by reinforcing the loaded face sheet with a steel bar, and fracture testing of the test specimens was conducted over a range of tilt angles. The fracture toughness exhibited mode-mixity phase angle dependence, especially for mode II dominated loadings; although, the fracture toughness remained quite constant for mode I dominated crack loadings. The fracture process was inspected visually during and after testing. For specimens with H45 core the crack propagated in the core. For specimens with an H100 core, the crack propagated between the resin-rich layer and the face sheet.