This study sought to find out how effective instructions are in promoting language proficiency of EFL Tanzania university students. 350 students from the University of Dar es Salaam participated in the study, guided by four questions focussing on a) students’ overall proficiency after the instruction, b) their proficiency levels across various academic disciplines, and c) across instructional groups, and d) the gender comparison of the observed proficiency. After the pre-test, followed by three weeks of instructions, a post test was administered and the findings suggested marginal increase in students’ written English proficiency with variations between the instructional groups, academic disciplines and gender.