Written bilingualism represents a particular type of bilingualism that is not frequently approached. The aim of this study was to investigate the writing and reading abilities of second-generation immigrants, Spanish-English bilinguals in South Florida. 58 participants (36 females, 22 males; 18-39 years of age) were selected. Both parents were native Spanish speakers and the home language was Spanish; 37 were born in the United States and 21 were born in a Latin American country, but arrived to the US before the age of 10. Equivalent reading and writing tests were administered both in Spanish and English. Performance was significantly higher in English than in Spanish in the following tests: reading aloud (speed and errors), writing sentences, spontaneous writing number of words, and spontaneous writing errors (spelling and grammatical). When comparing those participants born in the US and abroad, no significant differences were found in Spanish, but in English; participants born in the US did better in reading aloud (errors), and spontaneous writing errors (spelling and grammatical). It was concluded that reading and writing abilities are in general higher in English than in Spanish in this group of bilinguals, which is correlated with the language used in the school they attended. This study emphasize the importance to analyze not only oral but also written bilingualism. Toward the future, it would be particularly important to study written bilingualism in other types of bilingualism.