In response to the call for improving teacher candidates' familiarity with the assessment tasks and format of the edTPA (Hildebrandt & Swanson, 2014), this single case study investigated the reflective writing development of Jena, a K-12 Spanish teacher candidate, and her evolution in a pedagogy that focused on the development of writing two reflective genres: personal private reflection (PPR) and critical academic reflection (CAR). Findings from functional linguistic analysis provide insights into the impact of explicit instruction in the organizational and linguistic features of CAR and clearly differentiate it in function and purpose from PPR. The linguistic analysis is supported by qualitative data regarding Jena's writing development and her performance on the edTPA. Data suggest that further research could investigate the positioning of PPR as a resource for developing CAR in ways that value the contribution of each type of writing in supporting the development of teacher candidates as individuals and as professionals.