Merrifield and Wang resins were successfully converted to supported vinyl-functionalized solid supports with excellent yields by reacting the Cl or OH functionality with an alpha,omega-difunctional spacer bearing a carboxylic acid group and a terminal alkene. The ruthenium initiator (PCY3)(2)Cl2Ru=CHPh (Grubbs I catalyst) was then immobilized on the resins via cross metathesis (alkylidene exchange) and was used to initiate ROMP of norbornene. Number-average molecular weight and polydispersity index of the grafted polymers were determined after cleavage of the ester link between the resin and the spacer. The results showed a competition between ROMP and intramolecular "ring-closing" metathesis and/or intermolecular "cross" metathesis, which leads to an overestimated ruthenium initiator loading. (C) 2007 Elsevier B.V. All rights reserved.