This article reports on an exploratory qualitative study on 37 students' acquisition of language and literacy. The study closely analyzes a linguistics assignment written in English, the dominant language, given to students at University of the Western Cape belonging to groups speaking English, Afrikaans, or an African language. The study demonstrated that a variety of aspects of a student's learning biography influence her written performance. Proficiency in the dominant language is a necessary but not sufficient condition for successful written performance. The way the dominant language is taught and acquired interacts with various sociocultural and economic factors, to produce a student's full learning experience. Much of this interaction is traceable in the kinds of essays students produce. The article cautions against attributing significance solely to proficiency in the dominant language and against treating all members of the group of students for whom the dominant language is an additional language in the same way. A more important factor to consider is the students' differing degrees of familiarity with academic discourse, which is influenced by the students' socioeducational background. Biographical Data of the 37 Student Participants is appended. (Contains 3 tables and 4 footnotes.)