80 teams joined the league, including 63 promoted from the 1986–87 Tercera División after the expansion to four groups.
The composition of the groups was determined by the Royal Spanish Football Federation, attending to geographical criteria.
Teams from Andorra, Aragon, Basque Country, Balearic Islands, Castile and Leon, Catalonia, La Rioja and Navarre.
Teams from Andalusia, Canary Islands, Castile and Leon, Castilla–La Mancha, Extremadura and Madrid.
Teams from Andalusia, Aragon, Castilla–La Mancha, Ceuta, Melilla, Region of Murcia and Valencian Community.