The term of the Cortes of Castile and León expired four years after the date of their previous election. The election decree was required to be issued no later than the twenty-fifth day prior to the date of expiry of parliament and published on the following day in the Official Gazette of Castile and León, with election day taking place between the fifty-fourth and the sixtieth day from publication and set so as to make it coincide with elections to the regional assemblies of other autonomous communities. The previous election was held on 8 May 1983, which meant that the legislature's term would have expired on 8 May 1987. The election decree was required to be published no later than 14 April 1987, with the election taking place no later than the sixtieth day from publication, setting the latest possible election date for the Cortes on Saturday, 13 June 1987. The Cortes of Castile and León could not be dissolved before the date of expiry of parliament except in the event of an investiture process failing to elect a regional president within a two-month period from the first ballot. In such a case, the Cortes were to be automatically dissolved and a snap election called, with elected procurators merely serving out what remained of their four-year terms.
Parliamentary status
The Cortes of Castile and León were officially dissolved on 14 April 1987, after the publication of the dissolution decree in the Official Gazette of Castile and León. The table below shows the status of the different parliamentary groups in the Cortes at the time of dissolution.
Parties and candidates
The electoral law allowed for parties and federations registered in the interior ministry, coalitions and groupings of electors to present lists of candidates. Parties and federations intending to form a coalition ahead of an election were required to inform the relevant Electoral Commission within ten days of the election call, whereas groupings of electors needed to secure the signature of at least one percent of the electorate in the constituencies for which they sought election, disallowing electors from signing for more than one list of candidates. Below is a list of the main parties and electoral alliances which contested the election:
Opinion polls
The table below lists voting intention estimates in reverse chronological order, showing the most recent first and using the dates when the survey fieldwork was done, as opposed to the date of publication. Where the fieldwork dates are unknown, the date of publication is given instead. The highest percentage figure in each polling survey is displayed with its background shaded in the leading party's colour. If a tie ensues, this is applied to the figures with the highest percentages. The "Lead" column on the right shows the percentage-point difference between the parties with the highest percentages in a given poll. When available, seat projections are also displayed below the voting estimates in a smaller font. 43 seats were required for an absolute majority in the Cortes of Castile and León.
