Multiple scales measuring a customer's, or consumer's, engagement (CE) with a brand or specific brand elements (e.g., advertising/social media content) have been proposed in the literature, offering researchers different options to gauge CE. However, the myriad proposed operationalizations can yield confusion among scholars regarding how to best capture CE, exposing a growing issue for CE research. Addressing this issue, we take stock of major scales measuring a CE with a brand or specific brand elements. To achieve this objective, we performed a systematic review of major CE scale development articles (2005 to January 2023) using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) approach. We systematically evaluated these scales in terms of their respective CE conceptualization, dimensionality, itemization, and underlying theoretical perspective. We also identify potential scale-related risks, or pitfalls, exposing important insight for CE researchers.Overall, the results suggest the existence of theoretical contamination in specific CE measures (e.g., through the inclusion of related concepts in the proposed CE definition), compromising their theoretical rigor and raising a need for scholars to verify the theoretical underpinnings of their adopted CE scales.