Defensor Santiago was born Miriam Palma Defensor in Iloilo City, to Benjamin Defensor, a local judge, and Dimpna Palma, a schoolteacher. She was the eldest of seven children. She graduated valedictorian in grade school, high school, undergraduate school. She graduated high school in Iloilo Provincial High School (now Iloilo National High School) and served as the Editor-in-Chief (EIC) of the said high school's student publication ""The Ilonggo"". In 1965, Defensor Santiago graduated with a Bachelor of Arts degree in political science, "magna cum laude" from the University of the Philippines Visayas. After graduation, she was elected to the Pi Gamma Mu and Phi Kappa Phi honor societies.