Preface to the series. Preface. 1. P.P. Feofilov and the spectroscopy of activated crystals (A.A. Kaplyanskii and A.I. Ryskin). 2. Crystal field and electron-phonon interaction in the rare-earth ionic paramagnets (B.Z. Malkin). 3. Coherent transient and holeburning spectroscopy of rare earth ions in solids (R.M. Macfarlane and R.M. Shelby). 4. Experimental studies of energy transfer in rare earth ions in crystals (W.M. Yen). 5. Energy transfer in crystals (D.L. Huber). 6. Spectral migration of excitations in rare-earth activated glasses (T.T. Basiev, V.A. Malyshev and A.K. Przhevuskii). 7. Spectroscopy of collective states and co-operative transitions in disordered rare earth activated solids (V.V. Ovsyankin). 8. Ion-ion interactions and exciton effects in rare earth insulators (R.L. Cone and R.S. Meltzer). 9. Spectroscopic studies of Jahn-Teller phase transitions in rare earth crystals (R.T. Harley). 10. Studies of spin systems by means of light scattering in paramagnetic crystals (S.A. Al'tshuler, A.Kh. Khasanov and B.I. Kochelaev). 11. Electron paramagnetic resonance in the excited states of rare earth ions in crystals (R. Furrer). 12. Optical detection of spin-system magnetization in rare-earth activated crystals and glasses (V.S. Zapasskii). Author index. Subject index. Materials index. Cumulative index.