Tảng grew up in Saigon as one of six sons of a rich father who owned a rubber plantation and a printing house and taught ("for pleasure") at the Collège Chasseloup-Laubat; since his father intended him to be a pharmacist, after studying (exclusively in French) at the Collège Chasseloup-Laubat, Tảng was sent to Hanoi University for a year and then (after a delay caused by the violence attendant on the end of World War II in Vietnam) to France in 1946 to study pharmacy.

[3] While in Paris, however, Tảng was introduced to the movement for Vietnamese independence, met Hồ Chí Minh, and transferred to the École des Sciences Politiques, where he focused on military and diplomatic subjects and was especially drawn to Marxist writings on colonialism.

To avoid draft into the South Vietnamese army, he joined the newly created French School of Naval Supply in 1954.

[6] At the end of 1955, he took a job as Controller-General of the Viet-Nam Bank for Industry and Commerce, but he also became involved in opposition to the Ngô Đình Diệm government.

[citation needed] Through contacts that he had made during his studies in France, Tảng became involved in the anti-government activities in South Vietnam.

In April 1970, he was part of the escape of the Provisional Revolutionary Government when the military and civilian leadership of PRG and NLF were almost wiped out by ARVN forces.

While it was supposed to last only thirty days, the imprisonment of his younger brother, Bich, a director at the National Bank, was prolonged, and he was released only after many months of lobbying on the part of Tảng.

[13] The older brother, Quynh, a doctor who worked with the Health Ministry, was moved to a high security camp in the north where he was incarcerated at least until 1985.