Polyisoprene (PI) with pendent hydroxyl groups was synthesized by the radical copolymerization of isoprene and the hydroxyl containing comonomers 2-hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA), and methylenebut-3-en-1-ol (IOH). The reversible addition-fragmentation chain transfer (RAFT) controlled radical copolymerizations of isoprene with these comonomers were carried out at an initial hydroxyl mole fraction (f OH) of 0.03 in the bulk at 125°C. Aliquots of the polymerizing reaction solution indicated that copolymerization competed with the Diels-Alder reaction between the hydroxyl monomers and isoprene as well as the Diels-Alder homodimerization of isoprene. Significantly more IOH comonomer was incorporated into the copolymer (39 mol%) than either HEMA (23 mol%) or HEA (3 mol%). Furthermore, IOH polymerized at a rate similar to isoprene, which coupled with the slower Diels-Alder reaction resulted in hydroxyl functionalized copolymers with a more even distribution of comonomers. Additionally, only IOH copolymerized with isoprene under emulsion conditions at 25°C due to its limited solubility in water. The isoprene/IOH emulsion copolymers had hydroxyl monomer content close to fOH at complete monomer conversion. The utility of the hydroxyl functionalized PI was demonstrated by using it as a macroinitiator for the ring opening polymerization of d,l-lactide, yielding microphase separated polylactide graft polymers.