Purpose-When an organization becomes a high performance organization (HPO), it is able to outperform comparable organizations for an extended period of time, thereby ensuring its long-term survival. It is therefore imperative for these organizations embarking on an HPO transformation to be aware of the factors that will help make this transformation successful. Unfortunately the current literature does not provide these factors; one can only find factors influencing large-scale transformations. It could be argued that becoming an HPO is a large-scale transformation, but this leaves the question open whether there are specific factors that are important for this specific type of transformation. Design/methodology/approach-The purpose of this paper is to answer the research question ''What are the main factors which theoretically and in practice best support a successful HPO transformation?'' This question was answered using the results of a review of the literature on large-scale transformations and a review on the applications of de Waal's HPO Framework in practice. Findings-Eleven theoretical and eight practical success factors were found. These factors matched for 63.6 per cent, indicating there is a moderate overlap between what the theory predicts and what can be noticed in practice. In addition, the practical cases indicated there are two success factors that are specifically important for an HPO transformation. Originality/value-The study results contribute to the theory, as they show what is and is not important for a specific large-scale transformation such as an organization transforming into an HPO. The practical contribution of the study lies in the fact that organizations now know which factors to pay attention to in order to increase their chances on a successful HPO transformation.