This chapter examines whether the environment of Science Olympiads and competition tasks produced within the Olympiad framework can provide opportunities for teacher preparation for inquiry science teaching, both in pre- and in-service training. The chapter describes the Biology Olympiad (BiO) concept and then briefly discusses the question of competition (as a complement to cooperation) in relation to inquiry-based learning. With the aim of preparing a professional development programme for teachers, which introduces inquiry teaching through the concept of Biology Olympiads, which is popular in the Czech education system, the chapter presents the findings of previous research. This research started with systematic investigation of current pre-service and in-service teachers' expectations of and attitudes towards inquiry and the Biology Olympiad. The next part deals with secondary school students' experiences and attitudes related to participation in the Biology Olympiad and evaluation of the tasks in the Biology Olympiad from the perspective of their learning. The final part of the research summarizes an analysis of the tasks in the Biology Olympiad and evaluates their possible transfer into use in everyday classroom teaching. In conclusion, the chapter summarizes the facilitative potential, which the broader integration of Biology Olympiad tasks can have for upscaling inquiry-based science education (IBSE) in school biology teaching. [For the complete volume, "Professional Development for Inquiry-Based Science Teaching and Learning. Contributions from Science Education Research. Volume 5," see ED613991.]