English language and communication abilities are an essential part of the global engineering community. However, non-native English speaking engineers and students tend to be unable to master these skills. This study aims to gauge the perceived levels of their general English language proficiency, to explore their English communicative problems, to investigate their perceived abilities when performing English-related tasks in an engineering workplace communication situation, and to obtain feedback on student performances from English instructors in English for Specific Purposes (ESP) courses. The participants included 130 Thai undergraduate students and two English instructors at a government university. There were two instruments; a questionnaire for the students and a series of interview questions for the instructors. The results revealed that (a) although the students perceived their abilities to be at a fair level, they experienced difficulty using productive skills in English communication; (b) the English-related tasks that the students performed best and worst in were reading and writing tasks respectively; and (c) in the ESP courses, the ability of the students to use English in the 'real world' was not dramatically improved, and (d) these students also had unrealistic language learning goals. These results would benefit both ESP instructors and stakeholders in terms of increasing awareness of both language and communication problems, and designing tailor-made courses that are a perfect fit for their students with regard to the contemporary engineering community.