All elementary, junior high and senior high schools must provide inquiry as one of the core requirements according to the 12-year curriculum for basic education. Several pioneer schools were officially appointed to develop exemplary inquiry courses. On the account of inquiring being a term that connotes different meanings at the same time, teachers may encounter many challenges when they attempt teaching collaboratively due to their different views about inquiry. Exploring different beliefs of teachers teaching different subjects allows educators to provide appropriate professional development activities. This study explored the views and practices of inquiry and inquiry-based instruction of teachers in the context and process of developing exemplary courses. We conducted semi-structured interviews with 11 teachers with different subject backgrounds (history, geography, citizenship, information technology, physics, chemistry, and biology) in a pioneer high school, where cross-learning areas inquiry courses were developed and piloted. We then applied the open coding technique to analyze interview transcripts, teaching plans, and class videos from these teachers. Findings from interviews show that most teachers considered inquiry as a form of problem solving. Nevertheless, natural science teachers viewed inquiry as a process, whereas social science teachers equated inquiry as content. Most natural science teachers preferred offering contextualized learning activities for students to frame research questions and conduct investigations. They also considered reading comprehension in English as the main threshold for retrieving references, and time and equipment were critical factors for curriculum development. Social science teachers usually emphasized providing research questions and guiding a whole-class discussion. Moreover, professional consultation on specific topics was a major demand for curriculum development. The results from classroom observation reveal that teachers spent more than 30% of classroom time on traditional didactic instruction. In addition, carrying out investigations was the main inquiry activities of natural science classes. We suggest that teacher educators should deepen schoolteachers’ epistemic knowledge and provide them with professional development activities in accordance with their views about the peculiarity of the discipline.