As much as possible, the monitoring, evaluation and research of programmes to improve the health of adolescents should include adolescents themselves. Not only must adolescents’ views be heard, but there is also increasing potential for adolescents and young people to participate actively as evaluators. Increasingly, youth-led participatory action research is undertaken, particularly in community settings. 

Unfortunately, adolescents are sometimes excluded from research because of confusion about whether they should be regarded as children or adults. Adolescents’ rapidly evolving capacity to make informed decisions is important for their consent and assent in data collection; as their capacities evolve, adolescents may be more capable of consenting for themselves. 

• Adolescents of all ages should not be excluded from research or data collection unless there is a risk to their safety or there is no benefit from their inclusion. 
• The evolving capacity of adolescents to make informed decisions should be central to considerations about their involvement as subjects of research and who should provide informed consent for adolescent participation. 
• Inclusion of adolescents in research and protection from research risk can both be achieved. To do so, research and data collection require nuanced understanding of adolescent development and the social contexts of adolescents. 
• Gender and equity should always be considered. This means including appropriate data disaggregated by age group (10–14 and 15–19) and sex, as well as ensuring that research is gender- and age-sensitive.
• Disadvantaged, vulnerable or marginalized adolescents should be included in research and data collection by prioritizing sex-disaggregated sampling of marginalized adolescents and by including them through inclusive community-based participatory approaches. 
• To the fullest extent possible, adolescents can be involved as local advocates, data collectors, analysts and researchers in evidence-generation activities.