The present disclosure relates to: (a) mandelate salts of atrasentan, (b) pharmaceutical compositions comprising an atrasentan mandelate salt, and, optionally, one or more additional therapeutic agents; (b) methods of using an atrasentan mandelate salt to treat nephropathy, chronic kidney disease, and/or other conditions; (c) kits comprising a first pharmaceutical composition comprising an atrasentan mandelate salt, and, optionally, a second pharmaceutical composition comprising one or more additional therapeutic agents; (d) methods for the preparation of an atrasentan mandelate salt; and (e) atrasentan mandelate salts prepared by such method.