The 30-year-old graduate student and her Jewish fiancé, Marc Mezvinsky, 32, announced their engagement in November and told friends they were looking to a possible summer ceremony.
The families have revealed no specifics about the wedding.
Representatives for Secretary of State Hillary Rodham Clinton and Chelsea Clinton declined to answer questions about it, noting the family's wish for privacy. In a February 7 interview on CNN, Hillary Clinton would go no further than to say her daughter hadn't yet found a dress.
That hasn't stopped the speculation. The bride and groom have a range of choices, including conversion or a melding their two traditions into one ceremony.
The talk has been strongest in the Jewish community. There has been more rejoicing than lamenting about this interfaith union that brings a former first daughter a step closer to the fold. Still, they wonder: Has Chelsea been searching for a rabbi along with her gown?
"If they had a Jewish wedding officiated by a rabbi, I think that would be something really positive," said Ed Case, president of InterfaithFamily.com, which supports Jewish outreach to interfaith couples. "It's so important for the Jewish community to have interfaith couples engaging in Jewish life."
Chelsea Clinton grew up attending Methodist church with her mother. Bill Clinton has been close to his pastor in Arkansas, but the Southern Baptist Convention rebuked him years ago over his support for gay relationships and abortion rights.
Last year, Chelsea, a graduate student at Columbia University's School of Public Health, was seen attending Yom Kippur services with Marc at the Jewish Theological Seminary in New York, the flagship for Conservative Judaism, according to news reports.
Mezvinsky is a son of former Pennsylvania Rep. Marjorie Margolies-Mezvinsky and former Iowa Rep. Ed Mezvinsky, longtime friends of the Clintons. His parents, who are divorced, had attended a Conservative Jewish synagogue in Pennsylvania.
High rate of intermarriage
Hillary Clinton has strong ties of her own to the Jewish community from serving as a senator from New York.
"She has probably been in more temples by far than either you or I," said Rabbi Jerome Davidson, rabbi emeritus at Temple Beth-El of Great Neck, which Hillary Clinton has visited.
No one is saying, though, what route Marc and Chelsea will take.
Conversion was the choice in one recent high-society mixed-faith romance. Ivanka Trump became Jewish to marry New York real estate executive Jared Kushner last year. But Chelsea does have other options if she would like to embrace Jewish traditions while remaining Christian.
Some rabbis will officiate at interfaith marriages even though major Jewish movements bar or discourage them from presiding. Interfaithfamily.com links interfaith couples with rabbis and cantors. Only a small number will co-officiate with clergy of another faith.
One of those is Rabbi Harold White, senior Jewish chaplain at Georgetown University, a Jesuit school, who performed the 2002 marriage of Ari Fleischer, press secretary under President George W. Bush, and Fleischer's wife, Rebecca, who is Catholic. The ceremony was co-led by a priest and included a chuppah, or canopy, which is customary for Jewish weddings, a traditional glass-breaking, and a marriage contract, or ketubah.
A Methodist wedding would be far less complex.
The United Methodist Church allows local congregations and pastors to decide whether they should allow weddings involving one partner who is not a baptized Christian. The denomination's Book of Worship allows ministers to adapt the wedding ceremony within limits, according to the Rev. Taylor Burton-Edwards of the Methodist General Board of Discipleship.
The high rate of intermarriage has been an obsession in the Jewish community, which has struggled with how welcoming it should be to mixed-faith couples.
Rabbi Steven Carr Reuben of Kehillath Israel, a Reconstructionist congregation in Pacific Palasades, Calif., said even if Chelsea doesn't have a Jewish wedding or convert, she should still be considered part of the community.
"There are Jews by birth and Jews by choice and Jews by association," said Reuben, who has officiated at interfaith weddings for years and presided at the 2003 vow renewal of Ozzy Osbourne and his wife, Sharon, whose father is Jewish. "She's marrying into the Jewish family."