As a child, Ms. Holton, 58, had a symbolic role in helping integrate Virginia’s public schools before graduating from Princeton and meeting Mr. Kaine at Harvard Law School. As he rose up Virginia’s political ladder, she achieved renown in her own right as a legal aid lawyer, family court judge and Virginia’s secretary of education, a job she resigned once her husband was chosen as Hillary Clinton’s running mate. Ms. Holton, who declined to be interviewed, first moved into the Virginia executive mansion in 1970 as the 12-year-old daughter of Gov. A. Linwood Holton Jr., a Republican, and his wife, Virginia, known as Jinks. She enrolled at a prestigious grade school recommended to her parents by their upper-crust friends. At Harvard Law, she met Mr. Kaine in a legal assistance program that focused on civil rights protections for inmates, and she worked for the Mental Health Legal Advisors Committee, interviewing the criminally insane about the conditions of their imprisonment. Ms. Holton made a name for herself as a lawyer for low-income families and foster children, and then as chief judge on Richmond’s juvenile court. When Mr. Kaine was elected governor in 2005, Ms. Holton resigned from the bench and returned to her childhood home, where as first lady she concentrated on foster care programs that helped keep older children with permanent families and extend their education.