This study investigates the effect of the science writing heuristic (SWH) approach on the quality of prospective science teachers' (PSTs) argumentative writing and their understanding of the components of argumentation in the SWH approach and their own learning. Ten SWH approach activities were implemented during the semester. The study was carried out with 31 PSTs. A case study design was used. Data included the SWH approach's grading rubric and semistructured interviews. While the ANOVA and Bonferroni tests were used to analyze the SWH approach's grading rubric, content analysis was used to analyze the semistructured interviews conducted with 12 PSTs. The ANOVA results showed a statistical difference among the writing performance of the PSTs (F = 14.493, p < 0.01). The findings gathered from the interviews revealed that the quality of the argumentative writing and research skills of the PSTs increased over time. The PSTs made explicit associations among their beginning questions, data and observations, and claims and evidence, and they made distinctions between their data, observations, and evidence. Multiple representations played an important role in providing evidence to support claims. Moreover, the process of negotiation helped PSTs learn more effectively, and they believed that the argument-based inquiry lab was beneficial to their learning and their future vocational careers as teachers.