Through a critical lens, this chapter investigates complex processes that inspire basic education and university teachers in the Philippines to exercise language teacher agency (LTA), as well as the micro, mezzo, and macro factors that inhibit them from enacting it. It describes the role of language teachers situated in multilingual settings in implementing curriculum change and pedagogical innovation to overcome barriers and empower themselves and their learners. By examining illustrative cases involving both public and private school language teachers in basic and higher education, this chapter reveals how LTA is formed by contextual factors before and during the COVID-19 pandemic. Classroom observations and face-to-face and Zoom interviews with nine teachers reveal the value of using linguistic, technological, and personal resources in pedagogical innovations. The findings also confirm the importance of different types of support from the micro, mezzo, and macro levels in shaping LTA. It proposes a framework that describes the interplay among curriculum change, LTA, innovation, and support systems. It also offers practical recommendations that may benefit the fields of program development, materials design, and teacher education.