Photopolymerizable compositions containing photoinitiator systems that absorb in the visible are disclosed. The photopolymerizable compositions contain at least one ethylenically unsaturated monomer capable of free radical initiated addition polymerization and a photoinitiator system capable of being activated by actinic radiation. The photoinitiator system comprises a hexaarylbisimidazole, a chain transfer agent, and a sensitizer given by the formulae A or B wherein X and R.sub.1 -R.sub.13 are as defined herein. ##STR1##