Performance is a central concept in management because it is consistently a critical outcome of interest across levels of analysis and subfields. For example, organizational behavior and human resource management focus on individual performance, and strategic management centers on firm performance. Given the centrality of this construct, it is unsurprising that more than 200 theories of performance have been proposed. We used the CORE model of performance (i.e., Performance [P] = Capacity [C] + Opportunity [O] + Relevant Exchanges [RE]) to offer specific suggestions to confirm, refine, and refute performance theories at the individual and firm levels of analysis. Specifically, we recommend conducting six types of studies: (a) constructive reproducibility studies, (b) literal and constructive replication studies, (c) generalizability studies, (d) tests of competing theories, (d) empirical explorations of theoretical assumptions underlying existing theories, and (e) tests of previously published untested theories or theoretical models. We hope our article will help the management field improve the understanding of one of its most central constructs, not by creating new theories that seemingly offer “novel contributions.” Instead, we suggest improving our understanding of performance more meaningfully by confirming, refining, and refuting already existing performance theories.