In order to describe and compare sea ice salinity distributions, which are of interest in the study of physical and biological ice characteristics as well as ice-ocean interaction, we have computed composite profiles and fitted third-degree polynomials to salinity data of 129 cores from the Weddell Sea. Four characteristic profile shapes have been recognized and described through the polynomial coefficients (C-, S-, I- and ?-type profiles). The field data have been compared with ''ideal'' salinity profiles generated by a simulation scheme based on thermodynamic growth under climatological conditions representative of the Weddell Sea. Composite salinity profiles agree well with simulations, irrespective of the growth mechanism (i.e., frazil or congelation), suggesting that ice properties which depend on salinity or porosity may evolve independent of ice growth conditions. Analysis of salinity and 18O data in conjunction with the simulations demonstrates that apart from meteorological conditions controlling growth velocity and temperature distribution within the ice, flooding and upward brine expulsion are important in raising top salinities as frequently observed. Low top salinities are typical of ice that has undergone retexturing and differential desalination. Salinity decreases towards the bottom of a floe are a result of high oceanic heat fluxes and snow-cover effects. As a consequence of these processes the bulk salinity of Weddell Sea ice cannot be described by a simple linear age-thickness relationship as characteristic of Arctic first-year ice. ¿ American Geophysical Union 1992