The main aim of this chapter is to analyse parents' perceptions of children's assessment in primary school. Understanding these perceptions may shed light on their knowledge of assessment and involvement in their child's education. The sample population consisted of one hundred and eighty eight Spanish parents (N=188) of students in third grade in Asturias, Spain. Both qualitative and quantitative data were collected and analysed to understand: (1) parents' knowledge of students' assessment, (2) their interpretation and understanding of school reports, and (3) the need for further information and awareness to increase parental involvement. This chapter concludes with implications for parents' education and family-school partnerships that assist in developing a foundation for better practices.