An increasing number of U.S. Latinos are seeking to become more proficient in Spanish. The Spanish they may have been exposed to in childhood may not be sufficient when they find themselves as adults in more demanding environments, academic or professional. Heritage language learners appear in a wide spectrum of proficiency, from those who have a low level of speaking abilities, to those who may have a higher degree of bilingualism, but not fluent. Whatever the individual case may be, these heritage speakers of Spanish have different linguistic and pedagogical needs than those students learning Spanish as a second or foreign language. The members of the American Association of Teachers of Spanish and Portuguese (AATSP) have identified teaching heritage learners as their second greatest area of concern (after proficiency testing). Editors Ana Roca and Cecilia Colombi saw a great need for greater availability and dissemination of scholarly research in applied linguistics and pedagogy that address the development and maintenance of Spanish as a heritage language and the teaching of Spanish to U.S. Hispanic bilingual students in grades K-16. The result is Mi lengua: Spanish as a Heritage Language in the United States. Mi lengua delves into the research, theory, and practice of teaching Spanish as a heritage language in the United States. The editors and contributors examine theoretical considerations in the field of Heritage Language Development (HLD) as well as community and classroom-based research studies at the elementary, secondary, and university levels. Some chapters are written in Spanish and each chapter presents a practical section on pedagogical implications that provides practice-related suggestions for the teaching of Spanish as a heritage language to students from elementary grades to secondary and college and university levels.