The present invention is directed to catalytic compositions and to curable compositions containing them. Catalytic compositions of the present invention typically comprise: (i) a reactive compound comprising at least one group selected from acid-functional groups and/or groups that may be converted to acid-functional groups; (ii) a metal compound; and (iii) a compound different from (i) and (ii) that catalyzes an addition reaction between an ethylenically unsaturated compound and a thiol. Curable compositions according to the present invention comprise: (a) a polyene, (b) a polythiol, and (c) the afore-mentioned catalytic composition.