Although the importance of assessment on education is undebatable, the intentions of assessors while conducting assessment haven't been studied yet in detail. To this end, this study aimed to disclose pre-service and in- service English teachers' conceptions of assessment. In the study, conception of assessment was categorized under four main titles; improvement, school accountability, student accountability and irrelevance. A total of 97 pre-service and in-service teachers participated in the study. Descriptive results indicated that conception of improvement held the highest agreement level among participants. On the other hand, school accountability got the lowest agreement level. Correlation results showed that improvement, school and student accountability conceptions were positively correlated. A MANOVA analysis was applied to scrutinize any effects of gender and grade level/teaching differences on participants' conceptions. Analysis results indicated that both gender and grade level/teaching factors made significant difference on participants' conceptions of assessment. A follow up ANOVA analysis indicated significant gender difference on school accountability, with males had higher value than females. Also, there was a significant difference among grade level/teaching groups on school and student accountabilities. Teachers held the highest value for school accountability, and fourth graders held the highest mean value for student accountability.