Rosario Marin (born August 4, 1958) is a Mexican-American politician who served as the 41st Treasurer of the United States from August 16, 2001, to June 30, 2003, serving under President George W. Bush. She is the first person since William Clark to assume the post without having been born a United States citizen. She is the only foreign-born Treasurer of the United States.

Marin was born Rosario Spindola in Mexico City, Mexico. Her father Mariano, a worker in a label-making factory in California, brought his family to the United States in 1972 on visas provided by his employer. The move was initially resisted by Marin due to her upcoming quinceañera and her fear of leaving behind her customs and traditions. Marin's family settled in Huntington Park, California where her father obtained work as a janitor and her mother as a seamstress. They returned briefly to their old home in Mexico to celebrate a "small fiesta" in her honor.

Her poor command of English was another reason that Marin had resisted coming to the U.S. In high school, she was given an IQ test on which she scored a 27 out of 100 and was subsequently labelled as mentally disabled. This low score inspired Marin to work hard to learn the language which she accomplished in part by listening to songs on the radio and repeating the words. By 1976, she was in the top 20 out of a class of 500 and graduated with honors.

Marin's family had initially wanted her to forgo any further education and get a job in order to help out the family financially as well as help her mother care for her siblings. Marin compromised by working during the day and attending East Los Angeles College at night. After graduating in 1980, she continued to take night classes at the Los Angeles campus of the California State University (CSULA). Marin graduated from CSULA in 1983 with a Bachelor of Science in Business Administration.

Marin originally embarked upon a business and financial career. While attending CSULA, she had obtained work in 1981 at City National Bank in Beverly Hills as an assistant receptionist. After several promotions, Marin was poised for elevation to assistant vice president of the bank. However, in 1985 her son Eric was born with Down syndrome and she quit her job the following year in order to care for him. She also withdrew from an MBA program in which she was enrolled.

Her son's condition inspired Marin to become an advocate for the mentally disabled. During this time, she founded the first support group for Latino parents with Down's children as well as Fuerza ("Force"), an organization dedicated to providing services and support to mentally disabled children, and lobbied state officials in Sacramento on their behalf. It was also during this time, while counseling pregnant women with disabled children, that Marin became a supporter of abortion rights.

Marin's efforts came to the notice of state officials and, in 1992, she was appointed the chief of Legislative Affairs for the Department of Developmental Services by Governor Pete Wilson. At DDS, Marin worked for legislation to benefit the mentally challenged. Two years later, Marin was named chair of the Council on Developmental Disabilities where she continued to advocate for the mentally disabled and their families. For her work on behalf of the mentally disabled, Marin received the "Rose Fitzgerald Kennedy Prize" by the United Nations in 1995, the second person to receive the award.

Finally, in 1996, Marin was appointed the assistant deputy director for the Department of Social Services.