Research in the area of assessment for learning (AfL) has largely focused on generic approaches and strategies, applicable to teaching and learning in all subject areas. In this article, we address the issue of subject-specific approaches. We examine two lessons, one English and one mathematics, and we discuss the form of assessment for learning in the context of these two subjects. English and mathematics are often thought of as contrasting disciplines, typifying the arts/sciences split in education and there are significant differences in the social norms and the structure of knowledge in each subject. This article undertakes a comparison of the lessons in order better to understand how these significant differences affect the realization of formative assessment in the classroom, and in doing so finds much common ground which might be the starting point for future dialogue between the disciplines.