Unsustainable grazing practices result in degradation of arid and semiarid rangelands in southern Africa. Continuous grazing systems are often blamed for degradation, while rotational grazing systems are seen as more sustainable. The discussion about the impact of these grazing practices also has political and societal dimensions: continuous grazing is often related to communal farming while independent farmers are often economically able to subdivide large camps to rotate livestock and rest the rangeland. We evaluated 17 studies from southern Africa that compared the impact of continuous vs. rotational grazing on vegetation and found the outcomes to be contradictory and inconclusive. We identified several issues regarding the comparability of these grazing systems (such as differences in stocking densities, in herbivore composition and in spatial scale of data collection), making comparisons of the impacts of the two grazing systems ambiguous. Based on the evaluation of these studies, we list factors affecting the outcome of comparative rangeland studies that need to be considered when comparing rangeland management types. We conclude that only if comparative studies are designed to ensure result comparability, then the two management systems can be properly compared, thereby forming a basis for further research on sustainable grazing systems.