Lanthanide-containing nanoparticles have attracted much attention due to their unique optical properties and potential in nanotechnological applications. An amphiphilic block copolymer of poly(ethylene glycol)-b-poly(epsilon-caprolactone) methyl ether (mPEG-PCL) was functionalized with a dipicolinic acid (dpa) moiety and coordinated to lanthanide ions to afford [Ln(dpa-PCL-PEG-OCH3)(3)]-(HNEt3)(3) (Ln = Eu3+, Tb3+). Micelle-like nanoparticles of dpa-PCL-PEG-OCH3 macroligand and metal-centered polymers were prepared by solvent displacement methods. Dynamic light scattering analysis (DLS) and cryogenic transmission electron microscopy images confirmed the presence of solid sphere (<47 nm in diameter) and vesicle (>47 nm in diameter) morphologies. The viability and stability of the lanthanide complexes in micelle-like nanoparticles was explored by DLS and luminescence spectroscopy, and found to be stable for several weeks.