Abstract Current and recent advances in theoretical and experimental double beta (ββ) decay efforts are reviewed. Microscopic and schematic model calculations of Gamow-Teller matrix elements are briefly discussed. Emphasis, however, is placed on new developments in Quasiparticle Random Phase Approximation (QRPA) models and the controversy they generate in the case of neutrinoless (0ν) ββ-decay. The measured 2ν ββ-decay half-life, (1.1 −0.3 +;0.8) × 10 20y, of 82Se is discussed at some length. A detailed review of a number of experimental searches for ββ-decay in 76Ge, 100Mo, 136Xe, and 150Nd is also given. The experimental designs, construction materials, and current and projected sensitivities of these experiments are discussed.