This invaluable volume contains a biography of Nobel laureate Norman F Ramsey as well as reprints and retrospective commentaries on 56 papers relating to spectroscopy with coherent radiation. The earliest papers describe his work with I I Rabi, developing the then new magnetic resonance method and its uses to measure magnetic moments of the different forms of hydrogen and to discover the deuteron electric quadrupole moment. Later papers include his invention of the method of coherent separated oscillatory fields, the development of the atomic hydrogen maser and the uses of these methods to measure properties of nucleons, nuclei, atoms and molecules and to test parity and time reversal symmetries. Other papers present the first successful theories of nuclear magnetic shielding, NMR chemical shifts, electron-coupled nuclear spin-spin interactions and negative absolute temperatures.