Composite foam sandwich structures are considered high performance materials, however skin-core debonding and core failure are often a weak link in the structure. This is a follow on from the paper presented at Adhesion 19 which presented the results from plain composite sandwich panels for a range of foams, showing that the coarser cell foams introduce a thicker hybrid resin layer at the foam-composite interface leading to enhanced panel performance. This paper presents results from a study with a single foam looking at the effect of through-thickness reinforcement of the panels. The position of the through-thickness ribs was investigated by undertaking quasi-static three-point bend tests on the panels. Typical panel failure was due to shear in the foam extending to crack growth along the foam-skin interface. The best performance was found when the through thickness reinforcement was placed on either side of the central loading roller, thus constraining the spread of the damage. Effort was made to develop reliable FE models for the configurations considered thus providing a method of predicting the performance of other panel designs. The experimental data, which included load-displacement responses, failure mechanisms and full- field strain from digital image correlation, was used to assess the validity of the FE models developed. It was found that by using appropriate failure models for foam and skin the need for complex interface modelling was not necessary.