Embedded in the problem-solving paradigm and inspired by the process models presented by Bereiter and Scardamalia (1987), the present study set out to explore possible changes in writing processes over time. The longitudinal data were drawn from one group of students from a cross-sectional study (Albrechtsen, Haastrup and Henriksen 2008), that is 16-year-old learners, providing new data 18 month later. Think-aloud data in L1 and L2 from 17 Danish high school students were collected at two points in time. In line with findings from Time 1, the Time 2 data showed significant differences between processes in L1 and L2. However, no significant differences in processing over time could be established for either language, while significant differences were found for the quality of the essays produced over time for both languages. In an attempt to account for possible processing changes that might underlie the writing development over time, an in-depth analysis of a learner’s quality of processing is presented. Finally, implications for future research on the tracing of writing development as a complex ability (Cumming 2016) will be addressed.