Indicator history

The general term of residence is 10 years.

Five years be enough for those who have obtained refugee status and two years in the case of nationals of Latin American countries, Andorra, Philippines, Equatorial Guinea, Portugal or Sephardim.

Sufficient residence time in a year:
Who was born in Spanish territory.
Who has not timely exercised the right to choose.
The law which has been subject to guardianship, foster care or a Spanish citizen or institution for two consecutive years, even if he/she continue in this situation at the time of application.
Which at the time of application beareth one years married to Spanish or Spanish and is not in fact or legally separated.
The widow or widower of Spanish or Spanish, if the spouse's death there was no legal or de facto separation.
Born outside Spain The father or mother, grandfather or grandmother, who were originally Spanish.

In all cases, the residence must be lawful, continuous and immediately prior to the request.
 

Source: Civil Code: http://www.ucm.es/info/civil/jgstorch/leyes/ccivil.htm