This paper explores school principals' and teachers' views of the Italian teachers' appraisal system and related indicators. In particular, the research aimed at examining the opinions of school principals and teachers regarding the domains to be considered for teacher appraisal purposes. An investigation involving 37 school principals and 868 in service teachers, from three Italian regions, is presented. The data was collected through a questionnaire and statistically analysed. Findings suggest operationalising new data sources -- specifically students and parent, - is beneficial to evaluate teacher quality as a construct in data- based professional learning communities. They show different positioning: teachers seem to be really inclined to be evaluated, especially by students and parents, while school principals still seem very cautious in entrusting the teachers' appraisal to an external point of view. This paper adds to the existing research showing the perspective of a new teachers' appraisal, inspired by multi-faceted models based on multiple points of view (students, parents, not only principals) and not reduced to simplistic solutions of an accounting type. Furthermore, the study answers the call for research into teachers' appraisal as part of the professional learning actions and in view of more integrated professional leadership.