This paper examines the impact of discipline-specific language instruction on student writing in an English for Academic Purposes (EAP) course offered to civil engineering undergraduate students at a university in Hong Kong. Textual analysis of student scripts and student interviews were used to investigate the effectiveness of the course in helping students to write better Introduction and Literature Review sections for their Final Year Project reports. The great majority of students were able to produce effective texts which conform to the discourse conventions of academic writing in civil engineering. However it is difficult to separate the impact of language instruction on student writing from other influential factors. Two major pedagogical implications are drawn: the need for more scaffolding of input tasks and for more teaching of academic reading skills.