Eckstein moved to Boston in 1894, at first living with the novelist Martha "Mattie" Griffith Browne and still working as a teacher.[6] In response to her disappointment at the outcomes of the Hague Conventions she joined the American Peace Society, of which she became vice president between 1905 and 1911. She collected over one million signatures, signed by supporters from the US, UK, and Germany, for a proposal she had written prior to the second peace conference in The Hague. On 4 July 1907 she handed this document to Aleksandr Ivanovich Baryatinsky, who led the conference.