High school science and mathematics achievements in high-stakes testing environments are often characterised by poor performance and reduced participation by learners. The poor performance and reduced participation by learners in science and mathematics is often on the school improvement agendas. Making sense of how to improve learner achievements in science and mathematics is a school leadership function in addition to being a function of classroom practice. This study used an integrated model of school leadership to explore how a Pretoria high school made sense of how to achieve and maintain high learner performance in science and mathematics under the pressures of high-stakes testing. The single case study was purposely selected for consistently achieving high learner performance in science and mathematics. Narratives were elicited from conveniently selected positional leaders, a science teacher and a mathematics teacher. The study highlights integrated school leadership practices for resource and material mobilisation, fit-for-purpose teacher professional development and cultivation of a school culture defined by attitudes, values and work ethics to achieve and maintain high performance is science and mathematics. A recommendation for a further study is made.