The present invention is directed to a modular shoulder prosthesis having an adjustable radial offset and/or angular inclination provided by relative rotation of an adapter interdisposed between the stem and the head. Specifically, the interface configuration between the stem and the adapter, as well as between the adapter and the head are designed such that relative positioning of these components provides a continuous adjustment in the radial offset and/or angular inclination. Indicia are provided at the interface between the adapter and the head to precisely determine the magnitude and direction of the adjustment being made.