It is becoming widely accepted that teachers’ professional development (PD) is key when it comes to the development of instructional quality and student achievement. At the same time, results show slightly negative effects of the PD that teachers usually participate in (Kirsten et al., 2023). Considering the need to support teacher professionalization, frameworks of critical features of effective PD have been proposed, for example that the PD should include multiple sessions spread over a longer period of time (duration) during which teachers, together with their colleagues (collective participation), actively engage in activities such as planning and revising their instructional practices (active learning, e.g., Desimone, 2009). However, even PD programs designed according to these frameworks have difficulty demonstrating positive effects, especially if implemented on a larger scale (e.g., Jacob et al., 2017). The above issue is also evident in Sweden, where several national scale PD programs, corresponding to the core critical features frameworks, have been implemented during the past decade with effects that can be questioned (e.g., Lindvall et al., 2022). In particular, the collegial meetings in these programs seem to hold little potential for learning. The discussions during teacher meetings tend to focus on student characteristics and lesson design (e.g., group work or individual work) instead of critical discussions regarding instructional practices and teachers’ classroom actions (e.g., Kaufmann & Ryve, 2022). In order to support teachers to engage in constructive discussions about instructional practices with the aim of developing instructional quality, we have recently engaged in a combined research and developmental project, where we collaborate with four schools to try out and adapt QTR to a Swedish context. Based on data from surveys, interviews, and videotaped lessons pre and post teachers’ PD participation, we present results regarding how QTR has affected teachers' instructional practices and collegial collaboration, as well as how these effects are mediated by teachers' visions of instructional quality. The concept of instructional vision is of particular interest, given recent studies have shown that even though aspects such as teachers' education and subject knowledge can be important for the changes that are implemented in teaching, it is visions of high quality instruction that are of greatest importance (Munter & Wilhelm, 2020). Also, implicit national instructional visions in Sweden (in particular regarding the role of the teacher) can affect PD implementation (Kaufmann & Ryve, 2022; Ryve & Hemmi, 2019).

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