This volume contains the lectures and seminars presented at the NATO Advanced Study Institute on "Applied Laser Spectroscopy" the fourteenth course of the Europhysics School of Quantum Electronics, held under the supervision of the Quantum Electronics Division of the European Physical Society. The Institute was held at Centro "I Cappuccini", San Miniato, Tuscany, Italy, September 3-15,1989. The Europhysics School of Quantum Electronics was started in 1970 with the aim of providing instruction for young researchers and advanced students already engaged in the area of quantum electronics or wishing to switch to this area from a different background. Presently the school is under the direction of Professors F.T. Arecchi and M Inguscio, University of Florence and Prof. H. Walther University of Munich and has the headquarters at the National Institute of Optics (INO), Firenze, Italy. Each time the directors choose a subject of particular interest, alternating fundamental topics with technological ones, and ask colleagues specifically competent in a given area to take the scientific responsibility for that course.