Mathematical problem-posing (MPP) offers an alternative to teacher-directed approaches by encouraging students to create and solve their own problems. While MPP is supported by the Australian Curriculum and empirical research has increased over the last decade, implementation in classrooms is still limited. Using The Theory of Practice Architectures (TPA), this paper reports on data from the initial phase of teacher planning for MPP, part of a larger doctoral study exploring teacher practices during MPP and solving. This paper offers insights into the practice of planning for MPP and how the TPA can be used to capture the nuances of how practice is enacted in specific settings.