Such images were taken on set during filming, or as part of an organized photo-shoot, by a studio photographer. They were then disseminated to the media and the public to promote the film (see Film still).
This is definitely a film still rather than a screenshot, as the quality is too high and a stock code can be seen in the corner.
Public domain explanation
It is unlikely that this image was secured with copyright protection, as stated by film induustry expert Gerald Mast in Film Study and the Copyright Law (1989) p. 87:
"According to the old copyright act, such production stills were not automatically copyrighted as part of the film and required separate copyrights as photographic stills ... Most studios have never bothered to copyright these stills because they were happy to see them pass into the public domain, to be used by as many people in as many publications as possible."
If there is any chance that the photograph was copyrighted, under the terms of the 1909 Copyright Act (which was law until 1978) it would have had to be renewed 28 years after publication, otherwise it went into the public domain. A search for copyright renewal records of 1960 ([1], [2]) reveal no trace that this occurred.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
{{Information |Description=Publicity photograph for the 1932 film ''Disorderly Conduct'', featuring Spencer Tracy and Dickie Moore. |Source=http://www.acertaincinema.com/browse/person/spencer-tracy/?p1=1&p2=1&p3=1&p4=1 |Date=1932 |Author=Fox Film Corp