A new model for laser‐induced desorption is proposed based on a master equation for the photon population in a closely coupled subsystem involving the relevant degrees of freedom. The validity of approximations such as the Born and Markovian approximations is discussed in terms of the laser pulse duration and multiple time scales of the adspecies‐surface system. The desorption rate is numerically calculated from the photon population and the threshold number of photons absorbed by the adspecies. The effects of anharmonicity, dephasing and laser detuning on the desorption rate are examined. The mechanism of dephasing and the possible direct and indirect desorption channels are discussed.