The WAI is copyright, not in the public domain.
In 2016 I have gifted all my copyrights relating to the Working Alliance Inventory (WAI) to the Society for Psychotherapy Research (SPR). Henceforth all requests for reproduction or use of the WAI and related instruments to which I held copyrights should be addressed to SPR. Please contact the exacutive director of SPR Dr. Marna Barrett (email@example.com) for permissions associated with this instrument.
While I no longer own the copyrights and will not be involved in providing copyright release to requestors, I shall continue to support researchers using the instrument. If you have questions, or think I might be of assistance in your research project, send me an email at firstname.lastname@example.org with "WAI" (no quotes) in the subject line.
To get hold of various forms of the instrument:
You can get inspection copies of most of the material I have by clicking on the Downloads button in the menu bar.