This dissertation examines the skills, knowledge, and support needs of novice and experienced Languages for Specific Purposes (LSP) teachers in higher education in the United States. Using a critical ecological approach (CEA) framework, it aims to contribute to the global growing body of research on LSP teacher preparation that has thus far received little attention, by sharing best practices for the creation of LSP teacher trainings in local contexts. The study consisted of a mixed-method analysis of a 26-question online survey completed by 46 participants, along with 20 semi-structured interviews with survey participants who volunteered for those follow-up discussions. The quantitative data which consisted of Yes/No and Likert-scale questions was reported using percentage while the qualitative data was analyzed using a reflexive thematic analysis (TA) (Braun & Clarke, 2021) approach, which is consonant with a CEA in that it allows the researcher to take a "situated, partial, reflexive, critically-interrogative and radical" (Braun & Clarke, 2021, p.39) stance. Then, the data was coded through a multi-cycle process that led the researcher to construct themes which were subsequently compared and contrasted to the quantitative survey findings. Results indicate that most U.S. higher education LSP teachers had not received any pre- or in-service training to teach LSP courses, which is consistent with European findings. Furthermore, findings give insight into how some of these teachers were self-trained by using their research and transferable skills, but also by making use of the research literature that does exist in the field. Other relevant themes included six major curricular skills and knowledge-related needs identified by the survey participants i.e., general knowledge of LSP pedagogies and curriculum design, LSP as content together with language, the needs analysis (NA), community service learning (CSL) as a way to develop (inter)cultural competence, Task-Based Language Teaching (TBLT), and the use of online technology; in addition, participants identified five needs in the area of LSP teacher support, i.e., professional legitimacy, interdisciplinary collaboration, innovation, ongoing support, and sharing of resources. Implications from the results of this study point to the design and implementation of multi-formatted, locally-contextualized LSP teacher training programs rooted in a CEA. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]