We employ Monte Carlo computer simulations to investigate the simultaneous controlled radical polymerization in solution and from a flat surface. The bulk polymers grow at faster rates and possess narrower molecular weight distribution than polymers initiated from flat, impenetrable surfaces. The rate of surface-initiated polymerization depends on the density of initiator sites. Our results provide evidence that the assumption that the molecular weight of Surface-initiated polymers is equal to that of polymers grown in bulk, invoked often in determining the grafting density of surface-bound polymers, is generally invalid.