Abstract: Vinyl chloride polymers are heat-stabilized by formulating therewith heat-stabilizing amounts of (i) an organometallic salt couplet, (ii) at least one organic .beta.-diketone having the structural formula R.sub.1 --CO--CHR.sub.3 --CO--R.sub.2 and (iii) a substituted dihydropyridine having the structural formula: ##STR1## in which formulae R is alkyl or alicyclic having up to 20 carbon atoms, or phenyl, each R.sub.1 and R.sub.2, which can be identical or different, is a member selected from the group comprising hydrogen, a linear or branched chain alkyl or alkenyl radical having up to 36 carbon atoms, an aralkyl radical having from 7 to 36 carbon atoms, and an aryl or cycloaliphatic radical having up to 14 carbon atoms, with the proviso that R.sub.1 and R.sub.2 cannot both be hydrogen, and R.sub.3 is hydrogen or --CO--X, wherein X is R, or --NH--Y, with Y being aryl.