Biliteracy is a lifelong process shaped by social and educational factors. While some achieve full biliteracy, others struggle with semi-lingualism. This chapter explores key dimensions of biliteracy – contexts, media, content, and development – showing how language status and literacy traditions impact learning.

A case study follows a Spanish–English bilingual’s journey from being initiated in L1 writing to mastering L2 academic composition, illustrating multilingual education’s potential. However, many systems resist bilingual programmes due to cultural and political factors. This chapter examines biliteracy challenges in Ceuta, Melilla, and the United States, where policies shape outcomes.

Biliteracy is fluid – language dominance shifts over time, requiring educational support. Successful programmes recognize students’ linguistic repertoires, easing language transitions. Research confirms bilingual learners excel when home language literacy is included in instruction. This chapter will help to understand biliteracy’s evolving nature, which is key to building inclusive, effective education systems.