Teacher evaluation and certification is a proper approach taken to assess teacher knowledge base and to guarantee that teacher candidates are qualified and have met particular teaching standards. To this end, teacher-education university (i.e., Farhangian University) of Iran recently adopted a teacher evaluation and certification policy, nationally called ASLAH, which mandates all teacher candidates to earn a teaching certification by passing a comprehensive exam. The purpose of the present mixed-method study was to describe the development and validation of 'a written assessment framework', as one of the requirements of ASLAH project, that would measure English teacher candidates' professional knowledge and competency to teach English. The data were collected through a series of interviews with teacher educators and subject-matter experts (N=15), questionnaire surveys that involved 320 English language teachers, and test performance of 62 English teacher candidates. First, the study dealt with the development of the hypothesized framework that included items assessing teacher Content-Knowledge (CK) competency by virtue of nine domain-specific courses recommended by experts' qualitative and quantitative data. The items were empirically determined for content specification and validity, item difficulty and item discrimination. An initial piloting of the newly developed tool to teacher candidates showed tests as valid and reliable instruments for measuring teachers' CK competency. Perceived 'fairness', 'consequences', and 'quality of the results' of the present certification policy and practice were also explored from the eyes of all participants. The results showed that they were not negative about the possible test consequences and fairness. However they did not appear to be strongly positive about the practicality of teacher evaluation and certification project in the present context of teacher-education university. Policy recommendations and implications of the findings were discussed.