This paper draws upon a broader piece of research aimed at investigating the implementation process of a recent policy on teacher appraisal in Portugal. Two case studies were carried out and a combination of methods for data collection was used. Findings suggest that teachers' perceptions are marked by uncertainty and scepticism. Amongst the most critical issues are the lack of recognition of the appraisers, the bureaucratic and summative dimension, and the lack of necessary conditions to put it into practice. However, some positive aspects were also identified, namely the emergence of debates within the teaching profession, the opportunity to reflect upon teachers' practice and to change previous teacher appraisal system.