Critical thinking (CT) is a 21st-century skill critical in education and learning. Second language teaching has focused on language form, and there needs to be a shift from form-focused instruction to a function-focused paradigm, where students simultaneously practice language learning and deal with real-world issues in authentic contexts (Beckett, 2023). Project-based learning (PBL) with technology can facilitate such a shift, providing learners with authentic experiences of learning that would help them grow as critical thinkers and develop 21st-century competencies (Boss et al., 2015). Project-based language learning (PBLL) is the paradigm where form and function are taught together. This study explores how PBLL can facilitate CT and reflective writing in second language (L2) learners majoring in the English Translation program at a university in Turkiye. It also explores the issue of assessment in PBLL projects (Beckett et al., 2020). The study adopts Beckett's (2023) proposal for CT cultivation with PBLL projects focusing on social media studies to explore the impact of PBLL on CT and reflections and how technology facilitates CT in such projects and tests Chen and Hirch's (2020) assessment framework for assessing CT and disciplinary knowledge PBLL projects. Furthermore, it explores whether L2 learners benefited from explicit instruction about reflective writing in PBLL. Finally, the study explored L2 learners' perceptions of the PBLL approach. Fifteen participants completed a two-week project on climate change, where they collaborated to conduct research, analyze arguments on climate change online, and synthesize information in writing. As the final product, they designed a visual that summarized what they found and argued what needs to be done to reverse climate change. Finally, the participants learned how in-depth reflections can be written with the Borton (1970) reflective framework and the Knowledge Framework (KF; Mohan, 1986). They wrote a final reflection where they evaluated their research and learning experiences, and PBLL as a learning approach. This reflection assignment allowed participants to practice CT skills of evaluation and self-regulation (Facione, 1990). To explore how the participants used CT skills throughout the project, I conducted a qualitative discourse analysis with systemic functional linguistics (SFL) methods, particularly the KF. To explore PBLL assessment, I developed and used rubrics for project assignments, the final product, and individual reflection letters. To explore learner perceptions, I conducted an Attitudinal analysis using the Appraisal Framework (Martin & White, 2005). The findings showed that the PBLL project on climate change facilitated the use of CT skills in the participants. The rubric evaluations made throughout the project effectively assessed how the participants used various CT skills and technological competencies to address the project's requirements and driving questions (Boss et al., 2015). With exceptions, the participants have benefited from the explicit instruction of Borton (1970) and the KF heuristics in writing detailed reflections. The overall perceptions of PBLL were positive as the participants stated how projects allowed them to use CT skills in real-life contexts and cited the lack of CT in traditional learning methods; however, some participants also stated that projects are time-consuming and collaboration can lead to problems in their learning. The study thus provides valuable insights into the application of PBLL in enhancing critical thinking and reflective practices, offering a compelling case for the wider adoption of such methodologies in L2 education contexts. [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/en-US/products/dissertations/individuals.shtml.]