This study examined the practices and challenges of students’ assessment in ECCE in government primary schools (specifically “O”-class teachers) in Dehana Woreda, Ethiopia.  To achieve the purposes, qualitative research approach with case study design was used. The researches purposively selected five (5) clusters from a total of 13 and five (5) government primary schools from a total of 15in the Woreda. From those sample schools, five (5) teachers from a total of 10 “O”-class teachers and five principals from a total of eight (8) primary school principals were selected purposively. Semi-structured interviews were used as tools of data collection. Besides, the researchers used document and observation checklist to collect data to triangulate and complement the data collected through interview. The collected data were analyzed thematically using direct quotation, narration, paraphrasing and interpretive analysis techniques.The results revealed that though teachers and principals have the knowhow of the concepts of assessment, they lack the knowledge of purposes of assessment, principles of assessment and multiple methods and areas of assessment. Concerning their assessment practices, they mainly assess children’s learning progress in every fifteen (15) days at a regular session through tests and observation. Hence, the practices related to ECCE assessment were limited. Finally, it is recommended that, government offices, colleges and universities shall work to create awareness and give training to “O” class teachers and principals to improve their knowhow and practice of children’s learning assessment.