The repartition of nuclear charge in fission has a narrower dispersion than almost any other property connected with the fission process. T o a crude approximation, the distribution of nuclear charge between light and heavy partners L and H leads to the most probable charges (ZP)L and (Zp)= displaced from the respective charges ZA of 8-stability by the same amount for the two fragments (Glendenin rule of equal charge displacement ECD, 1946). The existence of shell offsets in the Z,i vs. A function for different neutron-and proton-shell regions must be considered. All available data for thermal fission U235 (nt~,,F) are examined critically. The data show sudden offset-like drifts (fine structure) that may well be associated with shell properties of the products before the "neck" has dissolved. It is shown that these data eliminate naive equal charge displacement ECD, also an older competitive prescription of constant charge ratio CCR for the products, and an empirical Russian prescription (Apalin et al., 1960). The data are also examined in the light of the postulate that fission gives minimum nuclear plus coulombic potential energy (Present 1947, Fong 1955, Swiatecki-Blann 1960, and it is shown that the present mass formulas give too much uncertainty three to four &decays from stability t o give a useful test, but that shell effects in masses must be retained. Data from charged-particle fission with energy deposit up to 40-50 Mev are in reasonable accord with the low-energy data on correcting for composition and neutron boil-off. It is concluded from experiment that Zp is a single-valued function of A, known to about f 0.15 unit for low-energy fission and f 0.25 unit for medium-energy fission, and that the fine structure very probably present is a n indication of intrinsic nuclear chemistry.The early thinking on the wartime Manhattan Project about nuclear charge distribution in low-energy fission, before any yield data were available, was based on the concept (1, 2) of constant charge ratio CCR. Professor Wheeler had suggested (4) a search for positron enlitters t o see how wide the charge dispersion might be: the results of crude searches in the products of U235 (n,h,F) were, of course, negative (5). Way and Wigner (7) postulated t h a t the charge would distribute t o give a minimum nuclear potential energy, and Present (8) postulated a minimum for the sun1 of nuclear potential energy plus coulombic energy (equal to final kinetic energy). Present took considerable pains to handle the coulombic term for polarizable spheres with non-uniform proton density.The identification of shielded nuclides4 36-hour BrS2, 19-day Rbs6, and 13-day Cs136 among the fission products gave the first experimental leverage on charge distribution. The first detailed treatment of the problem (5) established the classical rule, or prescription (3, 6) of equal charge displacement E C D ; namely that the nuclear charge distribution between light and heavy partners L and H leads to most probable charges Zp displaced from stability...