OBJECTIVE: Compulsivity refers to a tendency toward repetitive habitual behaviors. Multiple disorders have compulsive symptoms at their core, including substance use disorders, gambling disorder, and obsessive-compulsive disorder. The aim of this study was to validate a scale for the objective, transdiagnostic measurement of compulsivity. METHODS: The 15-item Cambridge-Chicago Compulsivity Trait Scale (CHI-T) was developed for the rapid but comprehensive measurement of compulsivity. Adults aged 18-29y were recruited using media advertisements, and completed the CHI-T in addition to demographic, clinical, and cognitive assessment. The validity and psychometric properties of the scale were quantified. RESULTS: A total of 112 participants completed the study. The scale yielded a normal distribution with very few outliers. It had excellent psychometric properties, with high internal consistency (Cronbach's alpha=0.8), and excellent convergent validity against gold-standard assessments of compulsive symptoms (each p<0.001 for gambling disorder, obsessive-compulsive, and substance use disorder symptoms). Total scores on the scale correlated significantly with less risk-adjustment on the decision-making task (rigid response style), and divergent validity was confirmed against other cognitive domains (response inhibition and executive planning). The above significant findings withstood Bonferroni correction. Factor analysis suggested the existence of two latent factors: one related mainly to reward-seeking and the need for perfection, and the other relating to anxiolytic/soothing features of compulsivity. CONCLUSION: The CHI-T, a scale designed to measure transdiagnostic compulsivity, appears to show excellent psychometric properties in a normative population and merits further investigation in the context of clinical patient populations, including in treatment trials.