A SELF-EXTINGUISHING POLYMER COMPOSITION IN LATEX FORM HAS BEEN PREPARED BY THE ADDING FROM 1 TO 10 PARTS BY WEIGHT OF TRIS(2,3-DIBROMOPROPYL) PHOSPHATE IN COMBINATION WITH A SYNERGISTIC AMOUNT (0.5 TO 3.0 PARTS BY WEIGHT) OF A SALT SELECTED FROM THE GROUP CONSISTING OF MONOAMMONIUM PHOSPHATE, DIAMMONIUM PHOSPHATE AND TRIAMMONIUM PHOSPHATE, TO A TERPOLYMER COMPRISING 2070 PARTS BY WEIGHT OF AN ARYL VINYL MONOMER AND 30-80 PARTS BY WEIGHT OF A CONJUGATED DIOLEFIN, AND 0.5-10 PARTS BY WEIGHT OF AN A,B-ETHYLENICALLY UNSATUARTED CARBOXYLIC ACID. IF DESIRED, A PORTION OF THE AMMONIUM SALT MAY BE ADDED TO THE LATEX DURING POLYMERIZATION AS WELL AS AFTER THE POLYMERIZATION.