The present study investigated the beliefs and efficacy of a teacher teaching English to students who were weak at the language. The objective of the study was mainly to investigate the beliefs and efficacy of the ESL teacher for teaching writing to weak learners. The research was a case study of the English Language teacher teaching Form Three class of students whose English proficiency was very low. An interview was conducted with the teacher to further probe the instructional strategies applied to enhance her beliefs and efficacy in her own capabilities to make learning happen in her classroom. Observations were made to investigate the teacher’s efficacy in teaching and the performance of the students specifically for writing. Results show the teacher’s beliefs of her students’ capabilities and their language needs helped shape the teacher’s instructional strategies. The teacher’s efficacy enabled her to decide to undertake the task of teaching writing to her students because she was confident in her ability. The teacher provided clues to the students to facilitate their learning. This kind of feedback from the teacher indirectly motivated them to learn. The teacher’s beliefs and efficacy contributed to her teaching practice and the instructional strategies that she used in turn enhanced her beliefs and efficacy. The study implicates that teacher’s beliefs and efficacy can assist the weak learners in improving their writing skills and also facilitate language learning.