This review presents systematized data on absolute probabilities of electronic transitions in diatomic molecules published between the beginning of 1961 and the end of 1973, and relative transition probabilites published between the beginning of 1966 and the end of 1973. The paper reviews theoretical relationships lying at the basis of experimental methods for determining absolute transition probabilities. Individual methods are not reviewed in detail, since the details can be found in the cited literature. The following material is tabulated: absolute probabilities of electronic transitions, the dependence of the dipole moments of electronic transitions on internuclear distances, and the Franck-Condon factors (Tables I, II, and IV, respectively), using all publications known to the authors. In addition to the complete systematization of probability data, the authors attempt to provide a critical analysis of published results with a view to selecting the most reliable. The recommended values of the squares of the matrix elements of the dipole moments of electronic transitions are listed in Table III. The last chapter compares calculations of the Franck-Condon factors obtained for different molecular potentials.