The instructional strategies implemented by the English as a Foreign Language (EFL) teachers in an international technical college in Saudi Arabia did not prepare students at an intermediate level of proficiency on the Common European Framework of Reference. As a result, more than 77% of the first-year students were not progressing to the specialized diploma studies in the second and third years of their learning journey. Thus, the purpose of this exploratory case study was to better understand the instructional strategies adopted by instructors and the barriers to students developing their English skills. Vygotsky's zone of proximal development (ZPD) served as a framework of the study because it is aligned with the purpose and it emphasizes the context of instructional strategies in understanding how knowledge and learning are constructed. Multiple sources of data and interviews with 8 participants were used to investigate the research problem. Data were analyzed using thematic coding based on the conceptual framework followed by open coding to discover any emerging themes. Data analysis revealed that the observed teachers did not implement the student-centered instructional strategies discussed in Vygotsky's conceptual framework or ZPD-informed strategies. By designing a professional development program to train teachers on student-centered instructional strategies such as feedback, scaffolding, and student engagement, the results of this study can be used to lead to positive social change by educating teachers on strategies to help students develop better English skills.