Olefin metathesis polymerization reactions are disclosed, and more particularly ring-opening metathesis polymerization of cyclic olefins with olefinic compounds, such as are derived from seed oils and the like, to form telechelic polymers. In one aspect, a method is provided for carrying out a catalytic ring-opening metathesis polymerization reaction, comprising contacting at least one olefinic compound with at least one cyclic olefin, in the presence of a ruthenium alkylidene olefin metathesis catalyst under conditions effective to allow ring-opening metathesis polymerization of the cyclic olefin, whereby the cyclic olefin polymer formed is terminated with the olefinic compound. The invention has utility in the fields of catalysis, organic synthesis, polymer chemistry, and industrial chemistry.