The growth characteristics of magnetron sputtered Co-22%Cr thin films on amorphous glass or carbon substrates have been investigated utilizing transmission electron microscopy,. X-ray diffraction, electrical resisivity and in-plane stress measurements. Results indicate that the initial deposit is “amorphous”, but that isolated islands of small crystallites form before the film reaches 5nm film thickness. By 10nm, well oriented grains with hcp c axis perpendicular to the film plane develop, and by 50nm, a twinned columnar microstructure is evident. As this occurs, the in-plane film stress becomes constant. Also, we have observed a distinct subgrain structure in the thinner films (10–50 nm), and this is reflected in the electrical resistivity. This cannot be accounted for by an “evolutionary selection” growth scenario, but must be related to the low surface mobility of adatoms at these low substrate deposition temperatures.