Mulligan replaces Dave Kosa, who coached Haddonfield from 2009 through last season.
Mulligan is regarded as one of the best players in South Jersey history. As Jackie Donovan, she was Gatorade's New Jersey Player of the Year in 1990, led Sterling to three straight South Jersey Group 2 titles, and finished her high school career with 2,516 points.
Mulligan, who was inducted into the South Jersey Basketball Hall of Fame in 2006, played four years at Penn State and was captain of the 1994 Nittany Lions team that won the Big Ten title and reached the Elite Eight of the NCAA tournament.
In her six seasons as Sterling coach, she led the Silver Knights to two South Jersey Group 2 titles as well as the Group 2 state title and Tournament of Champions crown in 2000.
A mother of daughters ages nine, eight, and five, Mulligan resigned from full-time coaching after the 2005 season but said she stayed involved at the youth level on a limited basis.
Mulligan, an elementary-school teacher in Cherry Hill, said she was moved to apply for the position because of the culture of support for extracurricular programs in the Haddonfield community.
"It's a great community," said Mulligan, who lives in Haddonfield. "People just want to give their time, want to give their expertise. Everyone is so supportive."