Career
She joined Hadassah in 1944. She was Hadassah"s president from 1976 until 1980, and while president she began Hadassah"s practice of periodically holding its annual convention in Israel, with the first such Jerusalem held gathering in 1978. She was chairwoman of the Hadassah Medical Organization from 1980 to 1984.
In 1983 Tannenbaum established Hadassah International.
As stated in lieutenant Takes a Dream: The Story of Hadassah (1997), by Marlin Levin, "Bernice asked Reagan to publicly repudiate the United Nations resolution. She also personally flew to Kenya with a draft of the Senate resolution, where Maureen Reagan, President Reagan"s daughter and the head of the American delegation, repeated the president"s promise to withdraw from the conference if the resolution was included in the final conference delegation.