Most research reporting that bilingual children exhibit enhanced cognitive skills and social awareness relative to their monolingual peers focusses on children raised and educated bilingually, making it difficult to pinpoint the degree of second language exposure necessary for such advantages to materialise. The current study measures the social and cognitive skills of Spanish children educated bilingually yet raised monolingually to explore (a) whether bilingual education alone confers advantages, and (b) whether greater second language exposure is key to producing them. It compares three groups of monolingually-raised children in their first year of primary education (i.e. 6-7 years old): one group educated in mainstream 'monolingual' education, one group enrolled in English-Spanish bilingual education with a ratio of 40-60 English-Spanish exposure, and one group enrolled in English-Spanish education with a ratio of 30-70 English-Spanish exposure. After one year of primary education, children attending bilingual education scored significantly higher than monolingual children on a sub-set of cognitive (selective attention; response inhibition) and social (communication; co-operation) skills, with the higher exposure bilingual school outperforming the lower exposure bilingual school on some of these measures.