Assessment is an integral part of instructional process. Several studies have identified assessment culture and practice in schools as a powerful factor affecting how teachers teach in the classroom. This study investigated how the nature of assessment in school affect implementing the Mathematics curriculum in primary grades in the Maldives. A total of eight teachers from four schools in two different locations of the Maldives participated in the study. The result showed that although curriculum encourages constructive approach to teaching and learning, the assessment practice in schools did not support the approach. Even though teachers’ perceptions of teaching mathematics were parallel to that of the curriculum, their instructional practices were significantly shaped by assessment practice in school. The finding suggests the need to align assessment culture and practice of schools to that of the curriculum in order for its successful implementation.