The eldest daughter Zipporah Maria Caetana and David Mendes Machado, Rebecca Mendes Machado was born in 1746. Both parents were Portuguese-born Sephardim. Indeed, family legend has it that her father was born a converso, and that her uncle was burned at the stake, a victim of the Inquisition. Her parents had been among the original Jewish residents of Savannah in 1733, though soon moved to New York where, in 1737 Machado was appointed hazzan of Shearith Israel. In December of 1747 her father passed away, and a few years later her mother remarried to Israel Jacobs. With that, the family moved once more, this time to Philadelphia.

In 1762 Rebecca married Jonas Phillips, a young German-born businessman who was, rather inauspiciously for their marriage, bankrupt. Through associates of her father, Rebecca’s new husband was able to secure a post as a shochet in New York. Not satisfied with the meager salary, he soon went back into business, and the family returned to Philadelphia before the Revolution.

The Phillips family grew in size and status. Rebecca gave birth to twenty-one children, including Rachel Machado Phillips Levy, Naphtali Phillips, Dr. Manuel Phillips, Aaron Phillips and Zalegman Phillips. Her husband served as parnas of Mikveh Israel, while Rebecca emerged as one of the first American Jewish women to take an active public role in communal life. In 1801, she co-founded the Female Association for the Relief of Women and Children in Reduced Circumstances, which provided charity to Jews and Gentiles. In 1820 she served as the first director of the Hebrew Benevolent Society of Philadelphia, the oldest Jewish women’s charitable organization in America, founded by Rebecca Gratz.