Summary: Sandwich beams with metallic foam cores can fail by several modes: face yielding, face wrinkling, core yielding and indentation. We estimate the initial failure load corresponding to the first deviation from linearity in the load-deflection curve as well as the peak load for each mode. Failure mode maps are constructed which illustrate the dominant failure mode for practical beam designs. The results of the analysis are compared with experiments on sandwich beams with aluminum foam cores in three-point bending, The peak loads and failure modes are described well by the analysis.