Born in Florida (a suburb of Buenos Aires, Álvarez Guerrero joined the Radical Civic Union of the People (UCRP, the more conservative faction led by Ricardo Balbín) in 1958 in his home town of Vicente López, a neighboring community.

[1] UCR Governor Carlos Nielsen appointed him subsecretary of social affairs, serving in that post until the military coup of 28 June 1966 which toppled President Arturo Illia.

That year he moved to San Carlos de Bariloche, where he practiced as a lawyer, taught philosophy and wrote for newspapers including La Nación and Diario Río Negro.

Upon the return of democracy, Álvarez Guerrero helped relaunch the UCR in Río Negro and was a leading player in the national internal Radical movement of Raúl Alfonsín and Conrado Storani.

[1] Following the coup of 1976, he was arrested and 'disappeared' for 72 hours, being released following protests by his party, including former President Illia, although he lost his passport and the right to leave the country.