Abstract: A liquid, radiation curable composition is disclosed that includes a reactive diluent to lower initial application viscosity without substantial reduction of cure rate. The composition of the present invention comprises: (a) an unsaturated polyester polymer; (b) a non-polymerized, cocurable polyfunctional vinyl ether component; and (c) a reactive diluent which is an unsaturated dioic acid ester having the following structural formula: ##STR1## wherein at least one of R.sup.1 and R.sup.2 is a group that includes an oxygen with a carbon adlacent thereto and an abstractable hydrogen attached to the carbon.