As education is one of the pillars of the social and economic development of modern societies, concern with the quality of pedagogical work and support systems for student learning should be permanent (Fernandes, 2008). The evaluation of teaching performance (ADD) was defined with the objectives of contributing to the improvement of the quality of the educational service and student learning, as well as to the appreciation and personal and professional development of teachers. In this sense, the current ADD system focuses on several dimensions, seeking to constitute itself as an essential mechanism for the development of educational organizations and trying to become a driver of teachers' personal and professional development. However, the implementation of teacher assessment has faced some constraints, and the pursuit of these objectives began to be called into question from the 2007/2008 school year onwards, with the introduction of unexpected structural changes. In fact, class observation became central to the ADD system and became the biggest controversy in its implementation (CCAP, 2009). If we combine this issue with the initial idea that no particular training would be necessary to implement the ADD system, we are faced with two facts that were at the origin of the tensions that were witnessed in the following years and that still persist today ( Rosmaninho, J. & Romão, P., 2021). Currently, in addition to length of service, to progress in the teaching career it is necessary to fulfill two mandatory requirements: continuous training, which is an aspect internalized in the teaching profession, and performance assessment (DR no. 26/2012) . After intense protests against the Ministry of Education (ME) and after years of freezing of teaching careers (of the 9 years and 124 days of freezing, teachers recovered 2 years, 9 months and 18 days), a consequence of the serious financial crisis of 2008 , the ADD system is finally in full application. Therefore, the true impacts of this system are only now being felt, both at an administrative and organizational level, and in terms of teachers' careers. The way in which this career was structured, namely with ordinance no. 29/2018, of January 23, which defines the rules regarding the filling of vacancies for progression to the 5th and 7th levels, causing the evolution in career is slower and makes it impossible for the overwhelming majority of teachers to reach the top of the career ladder. Currently, there is a situation of widespread discontent in schools regarding the ADD system, exponentiated by the lack of response to questions that arise in successive legal regulations that, in the meantime, have been regulating the system. Separate publications of Informative Notes from the Directorate-General for School Administration (DGAE) to clarify certain situations and the interpretation carried out by some schools, namely the Informative Note, dated 15 June 2020, which allows the application of an extra percentile when complaining/appealing the result of the performance assessment, they reinforce the distrust that teachers express about this assessment system. According to the Eurydice report (2021), teacher evaluation in Europe offers opportunities to improve both teacher performance and the quality of educational systems, noting that the dimensions evaluated must always aim at the teacher's performance in the classroom, but also an appreciation of their contribution to the school's broader objectives. Also according to the same report, in Portugal, the number of teachers who state that post-evaluation meetings are always organized, and who consider the feedback useful for improving their teaching practices, is significantly lower than the European Union level, (…) “seeming to suggest that teacher evaluation does not always fulfill its formative function” (Eurydice, 2021, p.125). According to Diogo (2021), with the unfreezing of the teaching career and the application of legal regulations, each teacher will have on average two progressions until 2023, and, at the same time, the integration into the career of a large number of contracted teachers, with the recovery of time of service, caused several “entropies” to the ADD system, of which the following stand out: the subversion of simplification and debureaucratization, the lack of preparation of internal and external evaluation devices, a huge number of teachers in need of external evaluation, causing the immediate need for a high number of external evaluators voluntarily. This project is not intended to call into question the existence of the ADD, nor the principles that define it, but to contribute to improving its effectiveness, efficiency and effectiveness, in an attempt to favor the improvement of the quality of the educational service and student learning. , as well as for the appreciation and personal and professional development of teachers. To this end, we propose to understand the different teaching sensibilities on this issue and identify the modus operandi of different Portuguese public schools, unveiling procedures and bringing teachers' perceptions on this matter to debate. Data will not be collected in the autonomous regions of the Azores and Madeira, as the reality and legal framework are different from that applied on the continent. In this study, the perceptions of teachers and other educational agents will be collected on how the ADD system, as well as the application of legal regulations that complement it, promote or not what is recommended in article 40, point 2 of the Career Statute Teacher (ECD): “Evaluating the performance of teaching staff aims to improve students’ academic results and the quality of learning and provide guidance for personal and professional development within the framework of a system of recognition of merit and excellence.”