In this paper we report a versatile and effective strategy to attain strong surface-enhanced infrared absorption by employing a sandwich system consisting of metal island films and self-assembled monolayers (SAMs) of 4-pyridinethiol, The observed larger enhancement factor stems from coupling of the electric fields induced by excitation of the surface plasmon resonance of the overlayer and underlayer Au island films, and from enhanced chemical interactions of the Au island films and the pyridine molecule in the sandwiched structures, compared to the corresponding SAM-Au configuration.