Communication: In this paper the synthesis and (co)polymerizations of 4-(acryloyloxy)-epsilon-caprolactone are reported. This new monomer can be polymerized in a living/controlled way by two different polymerization mechanisms: atom transfer radical polymerization (ATRP) and ring-opening polymerization (ROP). ATRP, which was carried out at 90 degrees C using NiBr2(PPh3)(2), leads to new polyacrylates containing pendant caprolactone functionalities with controlled molecular weights and narrow polydispersities (M-w/M(p)similar to 1.1). Alternatively, ROP of this functional epsilon-caprolactone bearing a pendant acrylate functionality leads to new poly(4-(acryloyloxy) caprolactone) as well as random copolymers when epsilon-caprolactone and L,L-lactide are added as comonomers. The (co)polymerizations were carried out using either (Al((OPr)-Pr-i)(3) in toluene at 25 degrees C or Sn(Oct)(2) as a catalyst at 110 degrees C producing (co)polymers with controlled molecular weights and narrow polydispersities (M-w/M(n)similar to 1.2). As a potential application, the introduction of acrylate pendant groups into the polyesters facilitated the preparation of cross-linked biodegradable materials either thermally or by irradiation with ultraviolet light radical curing.