The electoral law of 5 December 1958 (rearranged to allow for the National Assembly to appoint the president) guaranteed universal suffrage for all mature, literate citizens, but unofficially curtailed female participation.

All natural-born nationals residing in Portugal for the previous five years were allowed to stand for election.

The Chamber of Corporations, consisting of 200 members or more, was appointed by the government following the election to the National Assembly.

Although Caetano had made some effort to blunt the harsher edges of the regime, the election took place in an environment little different from the past 40 years.

Numerous opposition candidates bowed out of the race prematurely due to reportedly extensive harassment and voter manipulation.