The unprecedent times of the COVID-19 pandemic have had a relevant impact on schooling. In this context, identifying the features of effective and responsive teachers' professional development paths in the assessment domain has never been as critical as it is today. However, despite the widespread interest in teacher assessment literacy and despite the efforts of educational policies and teacher education programs, research continues to show that teachers are generally underprepared to face assessment challenges. The present article reports on an explorative study aimed at examining teachers' conceptions of assessment literacy, assessment practice, and professional development. Qualitative data are drawn from semi-structured interviews with 30 Italian primary school teachers. The descriptions of what they consider as assessment literacy and the qualities necessary for an effective assessment practice constitute the starting point for a wider discussion on the professional development drivers for being and becoming an assessment literate teacher.