The literacy in assessment is a skill lacking in a significant number of teachers, negatively impacting students’ educational progress. Hence, this study aimed to analyse the impact of a literacy and support program for teachers through authentic assessment training. The research conducted was exploratory in nature. It involved three teachers from schools in different districts of Chile, teaching Language and Literature at the 1st year of high school level, and three accompanying researchers. To determine the level of literacy, pre and post-tests were conducted, measuring the dimension of “gathering learning information”. Additionally, to assess the effectiveness of the intervention, teachers were required to enhance their latest evaluation tool according to the parameters of authentic assessment. The results revealed that teachers had a moderate level of assessment literacy and were unfamiliar with authentic assessment. Furthermore, no improvement in their evaluative competencies was observed following the support provided. These findings underscore the urgency of enhancing teachers’ assessment literacy, emphasizing the need for specific training opportunities in this area.