Previous results have shown, in agreement with the silicide‐growth theory of Walser and Bene´, that VSi2is the first silicide phase to nucleate and grow at single‐crystal‐Si–V interfaces. We have found that with sputtered thin‐film‐V–crystalline‐Si or amorphous‐Si diffusion couples we can reproducibly cause either VSi2or V3Si, respectively, to nucleate and grow. V3Si and VSi2are never observed together, suggesting that bistable growth can be triggered by the initial interface. The V3Si growth was found to have at1/2dependence and V was found to be the dominant diffusing species. This implies that unlike the case of VSi2, in V3Si the diffusion constant of V is much larger than Si and growth occurs at the Si‐V3Si interface. Deposition parameters and initial sample properties such as structure and impurity content which may control the nature of the reaction phase are discussed. We also find oxygen to be rejected by a growing A‐15 phase. Samples were studied by Rutherford backscattering, Seeman‐Bohlin x‐ray diffraction, and electrical‐resistivity–vs–temperature measurements.