The following was submitted by Sheila Mennell, Bradford Trust Fine Art:

Helen Stein was born Helen Steinberg in Odessa, Russia.  She came to the US at the age of 2, lived in New York and studied at the Art Students League with Max Weber.  She also went to Cooper Union. 

During the time she lived and worked in Paris (1927-1929), Sir Michael Crozer-Gielberg commissioned Le Corbusier to design a studio for her.
 
On returning to New York, she was an active member of and exhibited at the Society of Independent Artists  (1930-1939) .
 
For the last 10 years of his life, artist Marsden Hartley, who greatly admired her work,  became a close friend of  Stein's.  She did a noted portrait of him in 1932. 
 
On moving to Massachusetts, Stein was active in the Gloucester-Rockport art communities; she died in Gloucester, MA.
 
Sources include:
Peter Hastings Falk (editor) Who Was Who in American Art
Smithsonian Museum Archives of American Art
Society of Independent Artists
 
In 1988, artist Jay Friedline, a friend of both artists, donated to the Smithsonian Museum a collection of letters from Hartley to Stein along with 25 typed pages of anecdotes about Hartley, written by Stein.