ImportanceTubal sterilization is common, especially among individuals with low income. There is substantial misunderstanding about sterilization among those who have undergone the procedure, suggesting suboptimal decision-making about a method that permanently ends reproductive capacity.ObjectiveTo test the efficacy of a web-based decision aid for improving tubal sterilization decision quality.Design, Setting, and ParticipantsThis randomized clinical trial conducted between March 2020 and November 2023 included English- or Spanish-speaking pregnant cisgender women aged 21 to 45 years who had Medicaid insurance and were contemplating tubal sterilization after delivery. Participants were recruited from outpatient obstetric clinics in 3 US cities.InterventionParticipants were randomized 1:1 to usual care (control arm) or to usual care plus a web-based decision aid (MyDecision/MiDecisión) (intervention arm). The aid includes written, audio, and video information about tubal sterilization procedures; an interactive table comparing contraceptive options; values-clarifying exercises; knowledge checks; and a summary report.Main Outcomes and MeasuresThe co–primary outcomes were tubal sterilization knowledge and decisional conflict regarding the contraceptive decision. Knowledge was measured as the percentage of correct responses to 10 true-false items. Decisional conflict was measured using the low-literacy Decision Conflict Scale, with lower scores on a range from 0 to 100 indicating less conflict.ResultsAmong the 350 participants, mean (SD) age was 29.7 (5.1) years. Compared with the usual care group, participants randomized to the decision aid had significantly higher tubal sterilization knowledge (mean [SD] proportion of questions answered correctly, 76.5% [16.9%] vs 55.6% [22.6%]; P < .001) and lower decisional conflict scores (mean [SD], 12.7 [16.6] vs 18.7 [20.8] points; P = .002). The greatest knowledge differences between the 2 groups were for items about permanence, with more participants in the intervention arm answering correctly that tubal sterilization is not easily reversible (90.1% vs 39.3%; odds ratio [OR], 14.2 [95% CI, 7.9-25.4]; P < .001) and that the tubes do not spontaneously “come untied” (86.6% vs 33.7%; OR, 13.0 [95% CI, 7.6-22.4]; P < .001).Conclusions and RelevanceMyDecision/MiDecisión significantly improved tubal sterilization decision-making quality compared with usual care only. This scalable decision aid can be implemented into clinical practice to supplement practitioner counseling. These results are particularly important given the recent increase in demand for permanent contraception after the US Supreme Court decision overturning federal abortion protections.Trial RegistrationClinicalTrials.gov Identifier: NCT04097717