The interaction of Cu with the highly ordered S(4 x 4)/W(111) surface has been studied by means of Auger electron spectroscopy (AES). low-energy electron diffraction (LEED), and scanning tunneling microscopy (STM) at room temperature. The Substrate is a sulfur-induced nanoscale reconstruction of W(111) with (4 x 4) periodicity characterized by broad, planar terraces (similar to30 nm in width). We find that fractional monolayers of vapor-deposited Cu grow homogeneously as clusters on the S(4 x 4)/W(I 11) surface over a wide coverage range. At low, Cu coverages (< 0.1 ML), Cu nanoclusters are observed to nucleate preferentially at characteristic 3-fold hollow sites on the SO x 4)AV( I I I) surfaced there is a clear energetic preference for one type of site over others. The formed Cu nanoclusters are uniform in size (similar to0.6 nm) as coverage increases, indicating self-limiting growth. Evidence for long-range interactions that may affect the nucleation of nanoclusters is discussed. For coverages greater than or equal to0.1 ML. additional sites are populated, and the whole surface is decorated by Cu clusters. STM data are supported by LEED and AES measure merits. The results are interpreted in terms of heat of formation, relative reactivity, surface corrugation, surface diffusion, lattice mismatch, and long-range interactions in the nanoscale regime.