Voting was on the basis of universal suffrage, which comprised all nationals over 18 years of age and in full enjoyment of their political rights.

[3] The use of the electoral method resulted in an effective threshold based on the district magnitude and the distribution of votes among candidacies.

[4] The ruling Spanish Socialist Workers' Party (PSOE) designated former Foreign Affairs Minister Fernando Morán to lead their campaign.

[6] Adolfo Suárez had considered running as main candidate for his Democratic and Social Centre party (CDS),[7] but declined after the electoral law was amended by the ruling Spanish Socialist Workers' Party to make elected MEPs incompatible for posts in the Cortes Generales—Suárez was deputy in the Congress of Deputies, and would have been forced to renounce one of the two offices if elected.

In order to be entitled to run, parties, federations, coalitions and groupings of electors needed to secure the signature of at least 15,000 registered electors; this requirement could be lifted and replaced through the signature of at least 50 elected officials—deputies, senators, MEPs or members from the legislative assemblies of autonomous communities or from local city councils.