This paper examines how a standards-based form of assessment in operation in New Zealand has impacted upon the knowledge taught to secondary history students. The segmentation of history into assessable components along with assessment mechanisms which encourage the reduction in the number of standards being attempted has impacted upon both the breadth and range of historical content in history programmes. The reduction in knowledge is problematic as it diminishes learners' opportunities to draw connections between inter-related historical concepts from a wider knowledge base. Social realists have raised concerns about the reduced focus on knowledge in education and its effects in restricting students' development of conceptual knowledge which enables higher order, more abstract thinking. Experiences of standards-based assessment for history in New Zealand are indicative of this reductive phenomenon. In a culture of accountability, standards-based assessment, as enacted in New Zealand, may impede delivery of critical knowledge.