Background: Inquiry-based instruction is a prominent teaching strategy in science education that is assumed to be an effective means to foster not only students' understanding of science content but also their procedural and epistemic knowledge concerning inquiry processes. Empirical studies have repeatedly shown that inquiry-related activities should be combined with instruction that explicitly addresses procedural and epistemic knowledge to support students' learning effectively. Purpose: The aim of this study is to explore to what extent explicit instruction on procedural and epistemic knowledge is occurring in inquiry-based biology and chemistry lessons. Sample: The sample analysed in this study consist of 16 inquiry-based biology and chemistry lessons recorded in German classrooms. Design and Methods: The video recordings of the lessons were analysed in three steps. First, event-based codes were used to identify all phases of a lesson in which students were engaged in an inquiry-related activity (e.g. developing questions, planning investigations). Second, each phase was analysed with respect to features of explicit instruction (e.g. explications of inquiry strategies). Third, event-based codes were used to capture individual features of explicit instruction in a phase. Results: In our sample explicit instruction on procedural knowledge occurred rarely and mostly in the form of brief sidenotes rather than as a comprehensive and deliberately planned action. Furthermore, explicit instruction on epistemic knowledge was virtually non-existent. However, we observed that many tasks and questions that are given by the teachers during their lessons have a high potential for making procedural (and epistemic) aspects explicit. Conclusion: While this explorative study does not allow for causal explanations for the lack of explicit instruction, its findings provide important insights into classroom practice. Implications for teacher education and future research are discussed.