Evidence for the status of Black South African English (BlSAfE) as a variety of English is ambiguous. This paper examines 67 linguistic features of a corpus of BlSAfE student writing, the Tswana Learner English Corpus (TLE), in comparison to a Standard English reference corpus, the Louvain Corpus of Native English Speaking Students (LOCNESS), within the framework of Biber’s (1988) multidimensional model, to determine if evidence for indigenisation and systematicity exists. Linguistic features that occur more frequently in LOCNESS than the TLE suggest that LOCNESS is characterised by greater elaboration of information and information density, more syntactically complex subordination, more reference cohesion and more specialised meanings. The TLE shows evidence of greater involvement of reader and writer of the text, although some features of informality also occur in LOCNESS. Based on comparison of the coefficients of variation in the two corpora, it is concluded that they exhibit similar ranges of variation and that variety status cannot be denied to BlSAfE on the grounds of variability. The application of the multidimensional model shows that the reference corpus, LOCNESS, is similar to academic writing in four of the six dimensions, but differs in being more involved in style and more overtly persuasive. Superficially, the TLE appears to be quite similar to LOCNESS in terms of the various dimensions, but closer examination reveals a number of differences, which largely confirm the findings that were made on the basis of individual feature comparisons: The TLE carries a lower informational density, and information is more often presented in hypothetical ways. It shows a number of similarities with the style and the information processing strategies attributed to spoken registers, but it still remains very clearly distinguishable from spoken language. Many similarities between the corpora are observed, which should be attributed to the register features of student writing. The paper concludes that there is sufficient evidence to acknowledge BlSAfE as a variety of English, on the ground of the stylistic differences between the TLE and LOCNESS, particularly its greater interpersonal as opposed to informational focus, as well as discourse-functional differences in the use of linguistic forms.