She is a co-founder of the United States Holocaust Memorial Museum.[4] She was also the founding president of the Women's Group at the Friends of Sheba Medical Center, a hospital based in Tel HaShomer, Ramat Gan, Tel Aviv, Israel, from which she is the recipient of the Woman of Achievement Award.[4] She has endowed the Sigi and Marilyn Ziering National Center for Newborn Screening at the Sheba Medical Center.[5] Additionally, she has served on the Board of Directors of Temple Beth Am in Los Angeles, where she is a Hall of Honor inductee and recipient of the Torah Fund Award.[4][6] She served on the board of trustees of the Venice Family Clinic.[4] Moreover, she serves as one of four co-vice presidents on the board of directors of the American Friends of the Israeli Philharmonic.[7] She also serves on the Honorary Board of the World Alliance for Israel Political Action Committee (WAIPAC).[8]
She served as the chairman of the board of trustees of the American Jewish University (AJU) in Bel Air.[4] Shortly after her husband's death, she established the Sigi Ziering Institute Exploring the Ethical and Religious Implications of the Holocaust at AJU.[9] In 2008, she sponsored the "Symposium on Holocaust Education: A Tribute to the Voices Lost" at Syracuse University, her alma mater, co-organized by the United States Holocaust Memorial Museum, the Syracuse University School of Education and the Spector/Warren Fellowship for Future Educators.[3] In 2011, she sponsored the Alternative Spring Break to Montevideo, Uruguay, of students associated with Hillel: The Foundation for Jewish Campus Life at the University of California, Los Angeles (UCLA).[4] She has also donated to the Dortort Center for Creativity in the Arts at UCLA Hillel.[4]
In February 2013, she established the US$1 million Marilyn and Sigi Ziering Endowment for the Arts at Shalem College in Jerusalem, Israel.[10] The endowment led to the hiring of Roy Oppenheim as Professor of Music and Music Theory.[10] She also established the Sigi Ziering Fund for Philosophy and Ethics at Shalem College.[10] The fund endows the research of Asa Kasher, a co-author of the Israel Defense Forces's Code of Ethics, and Ruth Gavison, a human rights legal scholar.[10] She has also donated to Camp Ramah, a summer camp.[11]
She serves as one of five vice chairmen on the board of trustees of the Los Angeles Opera, where she has been a major donor.[12][13] In 2006, she made a US$3.25 million charitable contribution to the L.A. Opera for the performance of works by artists assassinated by the Nazi regime during the Holocaust.[11][14] The program, known as 'Recovered Voices,' was first suggested by conductor James Conlon.[14] However, it was discontinued in 2010 due to financial constraints.[15] In 2013, she revived the program at the Colburn School in Downtown Los Angeles, by donating US$1 million.[15] It came to be known as the Ziering-Conlon Initiative for Recovered Voices.[15]
In 2014, she was a Gold Sponsor of the Los Angeles Jewish Film Festival.[16]