Recently, electronic structure and band width of the system 1.2 monolayers Ni/Cu(100) have been found to be Ni-bulk-like [Mankey et al., Phys. Rev. Lett. 78, 1146 (1997)]. Therefore, we have traced the development of the electronic structure with thickness for various 3d transition metals using angle-resolved photoemission. All studied systems show similar behavior. We find, in contrast to the previous report, a very different electronic structure for the monolayer and for bull;. Moreover, our measured binding energies support the results of local-density calculations which obtain strong narrowing of the 3d band width of 1 monolayer Ni/Cu(100) as compared to bulk Ni.