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

All members of the Cortes of Castile and León were elected using the D'Hondt method and a closed list proportional representation, with an electoral threshold of three percent of valid votes—which included blank ballots—being applied in each constituency.

[19][20][21] By the time the UCD's executive had voted for the liquidation of the party's mounting debts and its subsequent dissolution on 18 February 1983,[1][22][23] electoral alliances with the AP–PDP coalition had only been agreed in some provinces of the Basque Country and Galicia.

[43][44][45] In March 1985, amid growing tensions, the PSOE replaced Madrid as their regional secretary general by Juan José Laborda.

[49] Despite Madrid's will to remain in the post and stand as candidate in the 1987 election for a second term in office, the judicial investigation compromised his personal position,[50][51][52] being forced to resign as regional president after his indictment for a societary crime on 29 October 1986,[53][54][55] though he would later be acquitted of any wrongdoing.

[56][57] José Constantino Nalda, who served as regional minister of the Presidency and Territorial Administration, was selected to replace Madrid in the post.