The fluctuation of the radius of gyration of a polymer chain is maximized under the critical conditions. The amount of fluctuations can be accessed from the theory using the Boltzmann distribution of the chain's states, eq 12. The dependence of the fluctuations on the solvent quality is depicted in Figure for the uncharged and weakly charged polymer chains. With increasing concentration of repulsive salt (panels a, d), the maximum in fluctuations (i.e., the critical conditions) is shifted to a better solvent quality (lower ε mer ). This corresponds to a lower LCST for ELPs. The opposite trend is observed for the attractive salt (panels c, f) where the solvent quality has to worsen to keep the critical conditions as the salt concentration increases. The relative shift of the critical solvent quality for the uncharged (c) and weakly charged (f) polymer is consistent with the difference in the standard free energy of the coil-to-globule transition obtained by simulations, Figure ). Let us stress again that the theory assumes a spherical geometry of the polymer and electroneutrality within this effective polymer volume. These assumptions are well fulfilled close to the critical conditions at 0.1 m salt concentration. For exam- ple, our mean-field theory cannot predict the radius of gyration of a charged polymer without salt as no explicit electrostatic interaction between charged monomers is included. Also at low salt concentrations, the effective radius predicted by the theory deviates significantly from the radius of gyration. In such cases, different approaches have to be used. Mean-field theory predictions for a negatively charged ELP Having verified the descriptive power of the mean-field theory, we use it now to predict the effects of salts to a negatively charged polymer. The set of salts remains the same, i.e., the cation is highly repulsive while the type of the anion varies. The solvent quality has to worsen to ε mer = 0.5 k B T to retain the critical conditions. The theory prediction is depicted in Figure (b), while the simulation results which we use for verification are shown in panel (a) of the same figure. To the best of our knowledge, no systematic experimental data are yet available for such setup. The simulation and theory results are in a very good mutual agreement. When the salt is added the collapse of the polymer chain is observed at first. The extend of the collapse is determined mainly by the (same) strongly hydrated cation and only mildly modulated by the anion type. Both electrostatic screening in the polymer and build-up of the osmotic pressure in the bulk solution contribute to the collapse. As the concentration of the salt increases, the anion-specific effects further drive the collapse or swelling, similarly to the case of an uncharged polymer. Contrary to the cationic polymer, neither the extent of the initial collapse dependents on the salt (anion) type, nor the isospheric point occurs. Consequently, the salting-out power of anions follows the direct Hofmeister series in the whole concentration range.