The purpose of this article is to analyse and interpret the effect of the primary school teachers' trade union in Greece insofar as the formation and realisation of education policy is concerned, and, more precisely, insofar as it concerns the issue of teacher evaluation. The research material used comes from the filing and analysis of the contents of the "Teachers' Forum," a periodical publication of the trade union, and from a field study on the role of school advisors within the context of teacher evaluation. What emerges as most telling from the findings is the impression that "evaluation" is perceived by the Teachers' Union of Greece as a concept that arouses reactions and resistance in its implementation. Consequently, an interesting line of research enquiry would be how local education administrators and teachers could be encouraged to create a climate of trust and mutual commitment.