Recording, narrative, exposition, and argument were hypothesized to present writing tasks of increasing cognitive and verbal complexity. This was investigated by obtaining writing samples in each mode from a stratified sample of 128 Australian sixteen year olds. The cognitive-complexity hypothesis was supported by data concerning the relative discriminative power of the four tasks, as reflected in the correlation between judges, the correlation between task scores and examination results, and the difference in performance of more and less advanced pupils as assessed by their schools. The verbal-complexity hypothesis was supported by significant differences among the tasks on words per phrase, phrases per clause, and clauses per sentence. The more advanced pupils showed greater flexibility in patterns of language use than did the less advanced pupils. (Author/AA)