Abstract: A time-lapse free-radical polymerizable composition which comprises (1) a free-radical polymerizable compound such as an ethylenically unsaturated monomer or a reactive polymer; (2) a soluble polymerization initiator such as a diacyl peroxide, a ketone peroxide; an alkyl peroxy ester, a dialkyl peroxide, or an inorganic persulfate; (3) a soluble, reducible metal chelate such as an iron or copper chelate in which the chelating agent is a .beta.-dicarbonyl compound having an enol content of at least 4 percent and a dicarbonyl angle of not greater than 120.degree., or a .beta.-hydroxy nitrogen-heterocyclic fused aromatic in which the hydroxyl group is attached to a carbon beta to the nitrogen in an adjacent ring; (4) a soluble organic reducing agent which is capable of reducing ferric ions to ferrous ions or cupric ions to cuprous ions; and (5) excess chelating agent in the amount of 10.sup.-.sup.4 to 2.5 moles of excess chelating agent per mole of reducible metal chelate.