Stable hollow polymeric nanocapsules with a cross-linked shell were prepared through an interfacially confined copolymerization of a monovinyl monomer and divinyl cross-linker via ail activator generated by election transfer atom transfer radical polymerization (AGET ATRP) in a miniemulsion system An amphiphilic block copolymer poly(ethylene oxide)-b-poly(n-butyl methacrylate) (PEO-PBMA-Cl) was used as a stabilizer/macroinitiator. The amphiphilic nature of the macroinitiator ensures that the polymerization starts from the aqueous/monomer droplet interface with polymer chains slowly growing inward in a controlled manner by an AGET initiated ATRP Characterization of the resulting particles by TEM, Cryo-SEM, and AFM provided direct evidence that nanoparticles with a hollow structure were successfully prepared. Introduction of cross-linking units to the shell of the particles improved the stability of the particles, which could be easily redispersed in some common organic solvents.