Lisa Yvette Sullivan GRD ’91, a dedicated children’s advocate and political organizer who helped New Haven elect its first black mayor, died Monday in her home in Washington, D.C. She was 40 years old.

The cause of Sullivan’s death is currently unclear.

The founder of the Black Student Leadership Network and LISTEN Inc., a leadership program for urban youth, Sullivan had become a nationally recognized youth advocate in recent years. She had previously served as director of the Field Division at the Children’s Defense Fund and had published work in several social policy journals.

After growing up in Washington D.C., Sullivan graduated from Clark University in Atlanta in 1983, before attending Yale to earn a master’s of philosophy in political science.

While in New Haven, Sullivan became involved in many political and social organizations. She served as adviser to the NAACP Youth Council in New Haven and became known as one of the most effective local political organizers.

She played a crucial role in the 1989 election of John C. Daniels, New Haven’s first black mayor. Daniels credited Sullivan with aiding in organizing voter registration drives that helped make his victory possible.

But Sullivan’s legacy in New Haven stretched far beyond that election or her time in the city, said those who worked with her.

“She affected a lot of people in different way and got a lot of people involved in New Haven politics,” said Henry Fernandez LAW ’94, New Haven’s economic development administrator.

Fernandez, the former director of Leadership, Education and Athletic Partnership, was a close friend of Sullivan’s and worked extensively with her during her time in New Haven.

“She cared very deeply about poor people and about the disenfranchised, and particularly looked to help young people find ways to take leadership roles in the community,” Fernandez said.