Before implementing the Competency-Based Approach (CBA) in 2003, the Algerian educational system was based on traditional teaching methods that focused mainly on acquiring the knowledge about language delivered by the teacher and the amount of information the learner could accumulate to pass the exams. Although CBA has shifted the teacher's role from a knowledge transmitter to a facilitator and the learner from a passive recipient to an active participant, the teacher-centered paradigm still prevails among secondary-school teachers. To shed light on that prevalence, the researcher attempts to explore the perceptions secondary-school teachers hold about Teacher-Centred Approach (TCA) and the reasons behind its widespread use. Therefore, the present study investigates the causes of TCA prevalence in English as a Foreign Language (EFL) classes using a mixed-methods approach. To reach that aim, the researcher put forward the following hypothesis. Although teachers know the various teaching approaches, they have to adopt the teacher-centered method because of several constraints. To collect the necessary data to identify those constraints, thirty English teachers from some secondary schools in the district of Mostaganem received a questionnaire. The research results confirmed the hypothesis stated above. They revealed that teachers are well-informed about the viability of various teaching approaches and methods; however, they keep adopting the teacher-centered approach. Such behavior is due to multiple constraints such as classrooms crowdedness, the traditional physical classroom environment, the baccalaureate (BAC) exam requirements, and the time restrictions due to the lengthy English programs.