In this study, we review the psychometric literature on mating effort and find that extant instruments (1) have not been adequately evaluated in terms of internal structure and measurement invariance, and (2) disproportionately focus on mate retention and intrasexual competition tactics designed to repel competitors, relative to attraction and investment effort. To address these gaps in the literature, we carried out two studies to develop and validate a new Mating Effort Questionnaire (MEQ). In Study 1, we report a pilot study in which participants’ responses to an item pool were submitted to exploratory factor analysis. In Study 2, we replicated the structure found in Study 1 using confirmatory factor analysis in an independent sample. A three-factor solution yielded the best fit. The three factors reflected respondents’ allocation of energy to attracting high mate value partners when already mated, seeking out romantic partners when single, and investing in their current romantic partner and relationships. Strong partial measurement invariance held across the sexes, implying that observed scores may be used to compare them. We also found evidence of concurrent validity via associations between the MEQ and constructs such as sociosexual orientation, K-factor, mate retention behaviors, and respondents’ sexual behavior. These findings suggest that the MEQ is a valid and novel measure of individual differences in mating effort which is well suited to complement existing mating effort measures.