Lesson planning is a core task for teachers, and pre-service teachers (PSTs) can learn how to plan lessons during internships. In this study, n = 200 PSTs were asked about their planning competency, and n = 121 lesson-planning documents written by PSTs were analyzed. The results demonstrate that PSTs considered their planning competency to be high and that this competency continued to increase during the internship. In addition, planning documents differed depending on whether they were used in an informal planning context or a formal situation such as an inspection. The perceived usefulness of lesson planning decreased over time.