Electron microscopy has been used to study very thin Nb‐Ge films sputtered‐deposited onto copper substrates. Micrographs and selected‐area electron‐diffraction patterns reveal an interface region between the substrate and the first A15 Nb3Ge to form. This interface consists of microcrystalline Nb‐N‐O and a two‐phase region consisting of Nb‐N‐O grains and an unidentifiable tetragonal Nb‐Ge phase. The A15 Nb3Ge grains which form later in the growth of the film exhibit the same grain size and shape as the Nb‐N‐O grains. From the results a model for the role of the interface in the initial formation of A15 Nb3Ge is proposed.