Tsai was born in Zhongshan District, Taipei, Taiwan on 31 August 1956, the youngest of 11 children of her father. Her father, Tsai Chieh-sheng (1918-2006), was a businessman who ran an auto repair shop, her mother Chang Chin-fong (1925-2018) was a housewife. Her given name, Ing-wen (英文), could be translated as "heroic literature" or "English language". During her middle school period, she studied in Taipei Municipal Zhongshan Girls High School. She studied law at the behest of her father. After graduating at the College of Law, National Taiwan University, in 1978, Tsai obtained a Master of Laws at Cornell University Law School in 1980 and then a Ph.D. in law at the London School of Economics in 1984. Upon her return to Taiwan, she taught law at the School of Law of Soochow University and National Chengchi University, both in Taipei.