This document summarizes a study on common grammatical errors in writing by English as a Second Language (ESL) learners at a Malaysian boarding school. The study has several objectives: to identify the most common grammatical errors, determine why these errors are committed, and provide suggestions to minimize errors. Previous research has found errors with pronouns, verbs, nouns, prepositions and more. Common causes of errors include interference from the first language and lack of grammar knowledge. The document reviews literature on grammar instruction, distinguishing errors from mistakes, common errors found in other studies, and perspectives on feedback. It concludes by outlining the research methodology, which involves a case study analyzing students' writing samples to identify errors and their causes