A structural analysis of an explanatory text written by a 12-year-old pupil is discussed to demonstrate how the PISA technique (the Procedures for Incremental Structural Analysis; Sanders & Van Wijk, 1996a) may contribute to the understanding of conceptual processes in writing. First, the validity of PISA is supported by showing that the hierarchical text structure corresponds with the (idiosyncratic) punctuation conventions of the writer. Then, it is explained how the writer's strategies and procedures can be reconstructed from the text structure. Evidence for the validity of these inferred cognitive plans is obtained from the distribution within the text of spelling errors, language errors, and self-corrections. Finally, the generalizability of these results is discussed together with the desirability of combining this off-line method with on-line techniques such as pause measurements.