Summary: As part of the effort to equip preservice mathematics teachers with the necessary secondary school mathematics content that they would need to deliver mathematics lessons, a school mathematics mastery test was implemented for all preservice mathematics teachers in the Postgraduate Diploma in Education programme in the National Institute of Education. This paper describes the rationale and the different phases in the implementation of this test, sample test questions, and the performance of the preservice teachers in the different batches since its implementation. The implication of the implementation of this mathematics content test and the future direction of study on preservice teachersâ€™ mathematics content knowledge are also discussed.