The effects of electron-electron interactions on the magnetic properties of alkali metals are reviewed. At the densities of the solid or liquid near the melting point, magnetic properties are well described by a generalization of the Stoner model. This approach accounts for enhancement of the magnetic susceptibility and deviations from the Korringa relation between the NMR Knight shift and the corresponding contribution to nuclear spin-lattice relaxation. When expanded by heating the liquid toward the liquid-gas critical point, the magnetic properties and optical reflectivity of caesium develop new characteristics best described by correlation enhancement of the effective mass. Behaviour of the Korringa relation deviation implies a change in the spin correlations from essentially ferromagnetic in the dense liquid to antiferromagnetic in the dilute metal. The similarity of these effects to those observed in the high T_c superconducting cuprates is discussed.