This chapter shifts focus to consider to what extent the behaviours viewed in Chapters 3 and 4 were unique to learners. This is achieved by using a new corpus, the TLC L1 corpus, which is composed of the same exam as in the TLC corpus. However, in this case it is L1 speakers sitting the exam. This allows us to see an overlap between the discourse unit functions selected by L1 speakers undertaking the same tasks as the L2 speakers. The role of micro-structural features, specifically grammatical features, in forming similarities and differences between the two sets of examinees (L1 and L2 speakers) is considered. As part of this, the chapter focuses in on four particular grammatical features – demonstrative determiners, numeral nouns, passives and relative clauses – which seem to link discourse unit to proficiency in the TLC to the extent that they generate differences between discourse unit functions when the TLC and TLC L1 are compared. The chapter also considers, however, the normative nature of the analysis undertaken and notes that individual learners’ performance may vary from the norms examined.