The paper addres­ses the issue of how the noti­on of com­mon or public weal can be spe­ci­fied for a demo­cra­tic poli­ty as a „coope­ra­ti­ve ven­ture for mutu­al advan­ta­ge“ (Rawls). It is argued that com­mon weal in demo­cra­tic poli­tics is to be unders­tood as its capa­ci­ty to pro­du­ce mutu­al advan­ta­ges for the citi­zen­ry and that the mea­su­ring rod for this capa­ci­ty is citi­zen sove­reig­n­ty, i.e. the respon­si­ve­ness of demo­cra­tic poli­tics to citi­zens‘ com­mon inte­rests. Sub­si­dia­ri­ty is ana­ly­zed as an orga­niza­tio­nal prin­ci­ple in poli­tics that can ser­ve as an instru­ment for advan­cing citi­zen sovereignty.