The role of nanoconfinement on the glass transition temperature (T(g)) of polymers has been extensively studied in the thin film geometry. This work looks at the T(g) of nanoconfined polystyrene (PS) in spherical nanoparticles (27-200 nm) , individually dispersed in crosslinked polybuthylmethacrylate matrices. A reduction of T(g) compared to the bulk was observed in PS nanospheres via neutron scattering mechanical tests and was found to decrease with decreasing diameter for D<50 nm . The general trend of T(g) depression in nanospheres was found to be similar to the results on thin film geometry.