Practice-oriented educational research is renowned for its impact, both in educational practice and research. Yet, existing studies on the impact of practice-oriented educational research reflect a proliferation of ideas on what impact is, can or should be. This study aims to contribute to an in-depth understanding by establishing a theoretically informed and empirically substantiated conceptualisation of the impact of practice-oriented educational research. Based on current literature, a tentative conceptualisation in the dimensions scope, nature and progress, representing the who, what and when of change, is proposed. The tenability and completeness of this conceptualisation is subsequently investigated in a qualitative empirical study. Based on interviews, individual reflections and small-group discussions, the impact of 10 purposefully selected practice-oriented studies in secondary STEM-education in the Netherlands is compared to the tentative conceptualisation of impact. This results in an empirical substantiation and extension of the tentative conceptualisation. The presented conceptualisation of impact of practice-oriented educational research in terms of "scope," covering educational practice and research within the context of a study or beyond, "nature," including conceptual, instrumental and symbolic change, and "progress," comprising sustainability, timeframe, and stability of change, can facilitate and focus discussions, considerations and analyses of the impact of practice-oriented educational research.