Inquiry-based science teaching (IBST) is promoted without any clear definition of the teaching strategies that are expected. The paper portrays the variety of the nature and development of teacher professional knowledge and practice regarding inquiry-based science teaching. It proposes and tests a model built upon six dimensions that represent the crucial characteristics of IBST: the origin of questioning, the nature of the problem, students' responsibility in conducting the inquiry, the management of student diversity, the role of argumentation, and the explanation of the teacher's goals. Each dimension consists of a continuum of four modalities that describe the variety of teaching strategies and range from teacher- to student-centred ways of performing IBST. This model is tested through an analysis of observations and interviews with 18 secondary science teachers who differ regarding their involvement in teacher collaboration and the length of their teaching experience. The model is capable of distinguishing three types of teachers in a way that is coherent with previous results: teachers engaged in collective settings perform more student-centred teaching strategies than experienced teachers who are isolated. This six-dimensional model of IBST might be of value to researchers and teacher educators who are confronted with the complexity of inquiry-based science teaching.