A curable composition comprises at least one monomer comprising at least one (meth)acryl group and a photoinitiator system. The photoinitiator system comprises at least one Type II photoinitiator and at least one cyclic -diketone represented by the formula (I) or a tautomer thereof. R.sup.1 represents an organic moiety having at least one free-radically polymerizable group. Each R.sup.2 independently represents H or an aliphatic group having from 1 to 12 carbon atoms, and up to two of oxygen and sulfur atoms, n represents 1, 2, or 3. ##STR00001##