This study seeks to examine teachers’ preferences for professional development features depending on contextual, individual and concept-specific factors. While reading skills of elementary school students vary widely (Frith, 1986; NICHD, 2000; Hussmann et al., 2017), results of intervention studies show that students’ reading performance improve particularly when there is a close fit between individual learning levels and the concept used for reading promotion (Bernard et al., 2019; Connor, 2019). Formative assessment seeks to address these two aspects through the implementation of a cycle of diagnostics, feedback and reading promotion: By (1) diagnosing students’ learning level, (2) conducting feedback sessions and (3) deriving an appropriate support measure, each child is provided with effective reading support appropriate to his or her learning level. However, the comparison of medium to high effects in reading interventions (Hattie, 2009) and low effects in school practice (Cheung & Slavin, 2016) visualizes that the implementation of such reading interventions is not automatically given when providing teachers with a reading concept only. Ultimately, the teacher is at the center of the implementation process, deciding if and how to implement a new concept in the classroom (Guskey, 1985; Clarke & Hollingsworth, 2002). Therefore, implementation research must focus on the question of what and how teachers need to learn in order to professionally use innovations in their classrooms (Bormann, 2011). Previous research on professional development (PD) has found that the design of PD activities plays a key role in the effectiveness of implementation. Specifically, Desimone (2009) provides five core features of effective professional development, which are (1) content focus, (2) active learning, (3) coherence, (4) duration, and (5) collective participation. However, the teachers’ perspective on Desimone’s core features remains unclear. Teachers’ ideas of appropriate duration for PD activities, for instance, may deviate from what research has shown to be effective and may therefore lead them to abstain from PD programs altogether. Consequently, it is important to ask teachers what and how PD programs should be designed to help them in successfully using evidence-informed innovations. Several studies have shown that teachers vary in response to the same PD, meaning that individual teacher characteristics and contextual factors such as composition of students and school characteristics have to be taken into account (Lipowsky & Rzejak, 2017). The extent to which perceptions of the environment and individual characteristics affect PD aspirations is highly relevant for designing more differentiated PD activities in the future. Thus, this study seeks to examine teachers’ preferences for professional development features depending on contextual, individual and concept-specific factors. To that end, four research questions will guide this study: 1. Do teachers’ preferences of PD differ from Desimone’s empirical features of effective PD? 2. How do aspects of the content (e.g., simple vs. complex) which are provided in PD influence teachers’ preferences for PD features? 3. How do individual teacher characteristics influence their preferences for PD features? 4. How do (perceived) contextual factors influence teachers’ preferences for PD features?