CONTEXT: Adolescents need support to make informed decisions about contraception. Few clinical questionnaires exist to help adolescents and their healthcare providers align contraception decisions with patient needs and preferences. METHODS: Our mixed-methods study involved a convenience sample of English-speaking, female patients aged 13-19 seeking contraception services at an adolescent reproductive health clinic in Colorado, USA. Qualitative interviews informed development of clinical questionnaire items. The questionnaire elicited demographic characteristics, pregnancy and contraception use history, preferred contraception attributes, peer and family involvement, healthcare information and support needs, motivations for contraceptive use, and barriers to contraceptive services. We identified key decision-making factors and reduced the number of questionnaire items through principal components analysis. Using multivariable analyses, we examined the correlation between questionnaire responses and current contraceptive method. RESULTS: Twenty individuals participated in interviews and 373 individuals completed the preliminary questionnaire with 63 candidate items. We identified five contraceptive decision-making factors: side-effect avoidance (eight items, Cronbach's alpha = 0.84), preferred method attributes (six items, Cronbach's alpha = 0.67), parental involvement (three items, Cronbach's alpha = 0.67), life goals prior to parenting (four items, Cronbach's alpha = 0.88), and access to a contraceptive provider (two items, Cronbach's alpha = 0.92) and nine stand-alone items. In multivariable analyses, we found that questionnaire responses for decision-making factors varied among participants using different contraceptive methods. CONCLUSIONS: Multiple priorities may influence adolescent contraceptive decisions. This clinical questionnaire can elicit these priorities before or during a healthcare encounter. Future studies should assess generalizability of the questionnaire and examine impact on method choice, continuation, satisfaction, and reproductive health outcomes.