He also authored more than a dozen books, including a biography of Che Guevara, and he regularly contributes to newspapers such as Reforma (Mexico), El País (Spain), Los Angeles Times (USA) and Newsweek magazine.

His father was Jorge Castañeda y Álvarez de la Rosa who served as Secretary of Foreign Affairs (1979–1982), during the administration of José López Portillo.

He graduated with an AB in history from Princeton University in 1973 after completing a 241-page long senior thesis titled "The Movement of the Revolutionary Left in Chile: 1965-1972.

Following a number of disagreements with other cabinet members Castañeda left the post in January 2003 and began traveling around the country, giving lectures and promoting his ideas.

In 2004, Castañeda started to seek Court authorization to run in the country's 2006 presidential election without the endorsement of any of the registered political parties.

[citation needed] In a Newsweek article published in March 2009, he suggested that Hugo Chávez was plotting a coup in Cuba due to concerns that Raul Castro would make concessions that would betray the Cuban Revolution.