Pedagogical knowledge has been the subject of theoretical and empirical studies. However, no research has so far integrated the existing scholarship with data to develop and validate a framework for pedagogical knowledge in English language teaching informed by lifelong-learning, complex-system perspectives. In the absence of such research, we used a mixed method research design through a systematic review of the literature, semi-structured interviews with experienced teachers (N=10) and teacher educators (N=10), as well as a survey of 336 practising teachers in Iran to: (1) develop a framework for pedagogical knowledge; and (2) validate this framework by designing a self-assessment questionnaire for pedagogical knowledge. Our analyses yielded a nine-component model that included: knowledge of subject matter; knowledge of teaching; knowledge of students; knowledge of classroom management; knowledge of educational context; knowledge of democracy, equity and diversity; knowledge of tests/exams; knowledge of learning; and knowledge of (professional) self. Within this nine-factor framework, each component of pedagogical knowledge consists of a number of subcomponents. The proposed framework highlights the multidimensionality and complexity of pedagogical knowledge, and the mutually constitutive relationships among different knowledge domains.