The current study aimed to develop and validate a Principal Emotion Inventory (PEI). Equipped with the theoretical-empirical strategy of test construction, this development and validation procedure consists of one expert survey and five sequential empirical studies with sufficient samples of participating principals based on existing emotion theories and empirical studies. The reliability, substantive validity, structural validity and external validity were tested using exploratory factor analysis, confirmative factor analysis, invariance analysis and structural equation modelling. As a result, a multidimensional model on principal emotions with 25 items was identified with a good model fit. The PEI consists of five factors: enjoyment, pride, frustration, anxiety and hopelessness. This paper is the first attempt to develop and validate a sound instrument that enables measuring school principals' salient emotions in relation to their working experiences. The PEI would provide a validated instrument for future research on discovering the nature of principal emotions as an independent construct. Measurement is critically important to the replicability and robustness of the research. The findings on principal emotions are also informative for principal preparation and evaluation while taking emotions into consideration.