Total current spectroscopy (TCS) has been used to study the growth of gold and silver on {100} vanadium surfaces. A slow transition from TCS curves characteristic of vanadium to curves characteristic of the noble metals is observed, accompanied by an increase in the net work function-more rapid for silver than for gold. Vanadium characteristics are lost from the TCS curves for mean overlayer thicknesses ≳ 15 A, and a simple analysis shows that the thickness of the surface zone from which TCS signals originate is approximately given by the electron mean free path. Observations of progressive attenuation of a characteristic vanadium feature with increasing mean thickness of overlayer permits separation into stages of nucleation and growth. There is a critical nucleus size of ≃ 2 A for silver and ≃ 4 A for gold.