Assessment plays a crucial role in teaching and learning process. Thus, teachers’ understanding towards assessment seems to be an important part to make sure that this process is in the right path. Past studies indicate that teachers are giving more priority towards summative assessment compared to formative assessment. This qualitative study aims to explore Malaysian secondary school teachers’ conceptions on formative assessment. Ten secondary school teachers were identified randomly to take part in this study. Data were gathered via semi structured interviews and document analysis. Thematic analysis was applied as data were categorized into the particular related themes. Data analysis revealed different understanding of formative assessment namely, testing and measuring, monthly test and enrichment activity. Additionally it was found that, teachers’ application of formative assessment matches with their professed understanding of formative assessment. Findings suggest that, teachers need continuous support from policy maker to make sure that they are on the right path in process of assessing students throughout teaching and learning process. Ongoing and onsite may best help them to have a clear understanding of formative assessment and how it can be integrated into teaching and learning.