When measurement models are not replicable and/or generalizable, clinical assessments become of questionable utility, and unreplicable findings from studies using those measures will follow. Inspired by recent examinations of measurement in neighboring fields of psychology, we propose a Registered Report, in order to evaluate the replicability and generalizability of 20 well-known and emerging measures assessing elements of romantic relationships and sexuality. After collecting a large sample of that is both sexually and relationally diverse, we will evaluate the taxometric structure, measurement model replicability, reliability, and generalizability of each measure across a multitude of theorized sources of noninvariance. Our results are likely to be of high value to clinical researchers and practitioners alike, as we identify which measures can produce credible assessments, while simultaneously revealing measures with limited replicability and/or generalizability, as well as relational and sexual concepts for which groups may have radically different mental constructions.