© 1994 Proceedings of SPIE - The International Society for Optical Engineering. All rights reserved. A theoretical model is presented to account for the experimental observation that infrared tissue ablation is optimized by the use of wavelengths near the amide II band of proteins. The model recognizes the partitioned absorption of IR photons between protein and water due to overlapping spectral features along with the dynamics of biopolymers, the loss of mechanical integrity in proteins, and the explosive role played by the vaporization of water. The theoretical foundation for this model can be found in previous accounts of thermal confinement, multicoinponent models , and selective photothermolysis.