This paper examines the acquisition of variable phonology in different speech styles with the purpose of establishing when the emergence of an adult-like command of sociolinguistic variables takes place in children's speech. Previous research has focused on describing general patterns of phonological acquisition, but little is known regarding the acquisition of variable phonology in Spanish. The findings of this research reveal that 54-71 month-old children are more likely to retain intervocalic /d/ in the controlled section of the interview. These results indicate that sociolinguistic variation in the sense of variation within the individual is emerging in this group of young speakers.