This study examines teachers' conceptions of assessment and related contextual factors at the classroom, school and national levels. A representative survey of Singaporean secondary school teachers resulted in a final sample consisting of 229 teachers from 9 secondary schools. Findings on that, teachers endorse views of assessment for school accountability, student accountability and student improvement, but little endorsement of assessment as irrelevance. Teachers report feeling capable and qualified to use assessments, but concerned about how much they are trusted as assessors at school and national levels. Follow-up latent class analysis identified groups of teachers based on their responses to the irrelevance of assessment; teachers who found assessment irrelevant were present across all schools and subjects, but showed lower sense of preparation for assessment, school-level support and importance of academic success in society.