Book excerpt: Bringing together contributions from some of the leading experts in the field of Spanish as a Heritage Language, this volume aims to provide an in-depth understanding of current and emerging trends in research and praxis. To this end, the volume is divided into three thematic units. The first unit surveys the study of Spanish heritage speaker bilingualism from a formal/theoretical linguistic point of view. The second unit focuses on issues shaping the current state of affairs in heritage language education. Finally, the third unit maps out future lines of development within heritage language instruction. The wide topical scope within this single volume will undoubtedly provide a valuable resource for researchers, students, and professionals working in different areas of Spanish as a heritage language.