Ion-assisted evaporation was used to study the stress and phase changes in thin Ta films. Using a series of ion energies from 63 to 500 eV, the stress in 100 nm thick films was changed from tensile to compressive by increasing the argon ion flux incident on the growing films. The resulting films were characterized primarily by x-ray diffraction and electrical resistivity measurements, as well as RBS. The resistivity in all sets of films shows a large decrease with increasing argon ion flux. The x-ray diffraction results are somewhat more complex, but suggest that increasing ion flux does change the amount of alpha phase present.