Currently, the Willingness to Engage in Consensual Non-monogamy (CNM) Scale (Journal of Social and Personal Relationships 32: 222-240, 2015) is the only known measure for assessing CNM desire among individuals who have never engaged in CNM. However, the factor structure and validity of this measure have yet to be tested. Further, scholars have yet to consider that this scale may measure different constructs across men and women. Given the magnitude and consistency with which previous work has reported gender differences in CNM research, it is worthy to critically evaluate this scale. The purpose of this study was to examine the factor structure and validity of the Willingness to Engage in CNM Scale. Additionally, this study examined the factorial invariance of this scale across men and women. Results from exploratory and confirmatory factor analyses using a large sample (N = 938) of college attending emerging adults (ages 18–29) supported a single-factor structure for all items in the scale. This study also found supporting evidence for convergent and divergent validity. A multigroup confirmatory factor analysis indicated partial measurement invariance across men and women. Implications for CNM research, methodology, and policy are discussed.