This study seeks to put forward a justified definition for the concept of Teacher Ownership, and establishes levels of science teacher ownership, based on a hierarchy of categories, using phenomenographic analysis. Such ownership is based on a meaningful science teacher internalisation of a motivational context-based teacher approach, established via a prior CPD programme. In so doing, the study distinguishes between teachers' self-efficacy levels attained at the end of the CPD and teacher ownership indicating the capability of propagating the desired teaching to students and other teachers. The phenomenographic analysis, based on semi-structured interviews, is carried out with 10 science teachers, 3 academic years after the administered CPD programme. From an analysis of perceptions, 3 distinct categories of sustainable science teacher ownership, based on 5 distinct teaching dimensions, reflect variations in orientation of teacher ownership. The main conclusions are that sustainable teacher ownership differs from terms such as a sense of ownership, towards ownership and self-efficacy and that, in this study, teacher ownership can be described as being exhibited by the science teachers in paradigmatic, experiential and emotional ownership categories.