BackgroundPatient agency in contraceptive decision-making is an essential component of reproductive autonomy.ObjectiveWe aimed to develop a psychometrically robust measure of patient contraceptive agency in the clinic visit, as a measure does not yet exist.DesignFor scale development, we generated and field tested 54 questionnaire items, grounded in qualitative research. We used item response theory-based methods to select and evaluate scale items for psychometric performance. We iteratively examined model fit, dimensionality, internal consistency, internal structure validity, and differential item functioning to arrive at a final scale.ParticipantsA racially/ethnically diverse sample of 338 individuals, aged 15-34 years, receiving contraceptive care across nine California clinics in 2019-2020.Main measuresContraceptive Agency Scale (CAS) of patient agency in preventive care.Key resultsParticipants were 20.5 mean years, with 36% identifying as Latinx, 26% White, 20% Black, 10% Asian/Native Hawaiian/Pacific Islander. Scale items covered the domains of freedom from coercion, non-judgmental care, and active decision-making, and loaded on to a single factor, with a Cronbach's α of 0.80. Item responses fit a unidimensional partial credit item response model (weighted mean square statistic within 0.75-1.33 for each item), met criteria for internal structure validity, and showed no meaningful differential item functioning. Most participants expressed high agency in their contraceptive visit (mean score 9.6 out of 14). One-fifth, however, experienced low agency or coercion, with the provider wanting them to use a specific method or to make decisions for them. Agency scores were lowest among Asian/Native Hawaiian/Pacific Islander participants (adjusted coefficient: -1.5 [-2.9, -0.1] vs. White) and among those whose mothers had less than a high school education (adjusted coefficient; -2.1 [-3.3, -0.8] vs. college degree or more).ConclusionsThe Contraceptive Agency Scale can be used in research and clinical care to reinforce non-coercive service provision as a standard of care.