BACKGROUND: Published guidance from the FDA, EMA, and ISPOR Task Force acknowledge that developing COA measures for use in adolescent populations (aged 12-17 years old) presents unique challenges beyond those found in other age groups. Recognized as a very diverse age group in terms of academic ability, specific aspects of COA measure development should be considered to ensure outcome measures are appropriate across the age range, such as age-appropriate vocabulary, language comprehension, understanding of the health concept being measured, and duration of recall. OBJECTIVES: To identify key considerations for including adolescent patients in qualitative COA development and selection of the most appropriate COA measures using example methods from several therapy areas. RESULTS: Many clinical studies have combined child or adult patient groups with adolescents, making it more challenging to determine adolescent-relevant outcomes. Grouping adolescents with either adult or pediatric patients can prove inappropriate from a measurement perspective; adolescent assessment may need to be conceptually different to that of adults (e.g. school vs work), while pediatric assessment techniques may not be well-received by older adolescents (e.g. faces response scale, juvenile language). Additional methodological considerations include issues around embarrassment and inhibition during interviews, use of creative tasks to elicit the concepts of interest, and proportionate representation within narrow age groupings to account for developmental differences and to determine the lower age limit at which patients can reliably self-report (i.e. observer-report is required). CONCLUSIONS: With a deeper understanding of the challenges faced when including adolescent patients in qualitative research, COA developers and researchers can better evaluate the content validity of assessments (concepts of interest) and appropriateness for the target population (context of use). Using patient-centered methods with adolescent patients in COA development will ensure the correct selection of COA measures to support endpoints in clinical trials with 12-17 year olds.