The establishment of TESOL as a professional field in the 1960s was led by the Center for Applied Linguistics (CAL), where Dick Tucker played a crucial role in shaping its missions and strategies and deconstructing diverse boundaries for understanding the profession and supporting teachers (Crandall & Tucker, 1990; Tucker, 1993). Due to its origin, TESOL programs are traditionally closely tied with the fields of applied linguistics and second language acquisition, with an emphasis on language learning and teaching. Over the past few decades as the number of English learners in U.S. schools and the need for qualified teachers have increased, many TESOL programs have begun offering training and preparation for elementary and secondary school teachers. The curricula of such licensure programs are accredited by the Council for the Accreditation of Educator Preparation (CAEP) and structured according to TESOL standards such as the Standards for Initial TESOL Pre-K-12 Teacher Preparation Programs (TESOL International Association (TESOL) Standards for initial TESOL pre-K-12 teacher preparation programs. Alexandria, VA: Author, 2019). Although the standards integrate applied linguistics/SLA into the field of education, some licensure programs, compared with others, tend to have more emphasis on education and instruction than on learning and acquisition. In this chapter, drawing upon our own experience and professional engagement in TESOL, we evaluate the distinct focuses of TESOL programs in U.S. universities, in particular whether they are more applied linguistics/SLA-oriented or education-oriented, to provide insights into varied practices in TESOL teacher preparation and development in the U.S. In this evaluation, we consider factors such as home department (where the program is housed) and its faculty expertise, academic level (undergraduate vs. graduate), and licensure vs. non-licensure offerings. Based on the evaluation, we offer recommendations for twenty-first century TESOL programs that cross the disciplinary boundary between applied linguistics/SLA and education by incorporating research and practices from both fields. [For the complete volume, "Crossing Boundaries in Researching, Understanding, and Improving Language Education: Essays in Honor of G. Richard Tucker. Educational Linguistics. Volume 58," see ED672546.]