Cause‐related marketing (CrM), a partnership between a for‐profit and not‐for‐profit company, is an increasingly common promotional approach. Consumers range in awareness of and knowledge about CrM, and vary in their ability to identify and evaluate critical elements of a CrM promotion. The authors describe this knowledge and ability as “CrM persuasion knowledge (CrM‐pk),” which guides consumer response, and can inform how firms use CrM promotions to communicate with consumers. In the current work, the authors define, develop, and evaluate an instrument to measure CrM‐pk, and examine how it moderates the influence of promotional features on consumer attitudes.