Multiphoton ionization of atoms in intense laser-lightfields is gaining ground as a spectroscopic diagnostic tool.In this volume, Delone and Krainov present their andothers' theoretical description of the process occurring inatoms under conditions of multi-photon impacts, inparticular, the shift, broadening, and mixing of electronicstates which complicate the interpretation of spectra.The topics of individual chapters include tunnelingionization, above-threshold ionization, ionization ofmultiply charged ions, resonance-enhenced ionization, super-intense radiation fields, and properties of Rydbergstates in strong fields.