In this study, a data feedback program to improve teachers’ science and technology (S&T) teaching skills was designed and tested. The aim was to understand whether and how the four design principles underlying this program stimulated the intended teacher support. We examined how teachers in different phases of their career applied and experienced the employed design principles’ key aspects. Eight in-service teachers and eight pre-service teachers attended the data feedback program and kept a logbook in the meantime. Group interviews were held afterwards. Findings show that applying the four employed design principles’ key aspects did support and stimulate in- and pre-service teachers in carrying out data feedback for improving their S&T teaching. However, some key aspects were not applied and/or experienced as intended by all attending teachers. The findings provide possible implications for the development and implementation of professional development programs to support in - and pre-service teachers’ S&T teaching using data feedback.