This chapter presents four main research paradigms in CALL (computer-assisted language learning) teacher education and professional development, namely, the traditional (cognitive) paradigm, the sociocultural paradigm, the ecological paradigm, and the critical paradigm. The cognitive paradigm, featured with TPACK and TA concepts, views teachers as technology users and emphasizes skill training. The sociocultural paradigm, reflected in situated learning, collaboration, and activity theory, sees teachers as mediators, frames technology use as socially shaped, and emphasizes learning as a socially situated process. The ecological paradigm, undergirded by complexity theory, treats CALL teacher development as complex and nonlinear, with teacher agency emerging from interactions within their ecosystems and contingent upon how the affordances of technologies are perceived and capitalized on by teachers. Finally, the critical paradigm, informed by an emancipatory mode of rationality, centres on digital inequality and social justice, urging teachers to become agents of change by addressing digital divides and algorithmic biases. Critical digital literacy is becoming one of the key objectives in CALL teacher education.