Quick summary: New research shows that peer influence during adolescence works through two distinct channels, with close friends having the greatest impact on emotional difficulties and conduct while popular peers set the norms that shape more visible behaviours such as social media use and body image. A study tracking 543 Lithuanian pupils aged 10–14 found that the type of peer relationship, rather than social standing alone, determines which behaviours are influenced and how. For mental health practitioners and educators, the findings suggest that interventions targeting anxiety or behavioural problems should centre on friendship dynamics, while efforts to reduce excessive social media use or appearance-related pressures require a focus on shifting wider group norms.

Teenagers are not influenced by their peers in a single, uniform way, according to new research that sheds light on how friendships and social hierarchies shape behaviour during early adolescence. The findings, published in Development and Psychopathology, suggest that efforts to address anxiety, social media use, and behavioural problems may need to account for distinct types of peer pressure rather than treating them as one and the same.

The study followed 543 pupils aged 10–14 in Lithuanian middle schools, tracking changes in their emotional well-being, behaviour, academic performance, and social media habits over several months. Researchers collected data twice within a single academic year, allowing them to observe how peer influence unfolded over time rather than relying on a snapshot.

Mary Page James, PhD, a developmental psychologist and lead author of the study, said the research was motivated by a gap in existing literature. “Peer pressure is often treated as a single, uniform process, but that oversimplifies how influence actually works in the adolescent social world. In reality, young people are embedded in multiple peer contexts, including close friendships and broader peer hierarchies shaped by popularity. Our goal was to bring these perspectives together and test whether different types of peers shape different kinds of behaviour.”

What emerges is a clear pattern. Best friends exert the strongest influence over internal and behavioural difficulties, including emotional problems, poor emotional clarity, and rule-breaking behaviour. Teenagers appear to become more like their closest friends in these areas, suggesting that intimate relationships play a key role in shaping mental health and conduct. This effect extends, to a lesser degree, into academic performance among older adolescents.

In contrast, behaviours linked to visibility and social positioning are shaped more by broader peer group expectations. Social media use is driven primarily by what is considered normal among popular students, with teenagers adjusting their online activity to match the behaviour of high-status peers. A similar pattern was observed for weight concerns among older adolescents, as awareness of social image grows and popular peers become more influential in setting shared expectations around appearance.

Close friendships operate through reciprocity, where maintaining harmony and similarity strengthens the bond. Peer group norms, by contrast, are driven by hierarchy, where popular individuals effectively set behavioural standards that others follow. James noted that this distinction carries practical consequences. “If we want to change behaviour, we need to understand who is driving it and tailor our approach accordingly.”

The study accounted for factors such as popularity, rejection, and number of friendships, ensuring the observed effects were not simply due to broader social standing. The results remained consistent, indicating that the type of peer relationship itself is what matters most.

James said the team plans to expand the research further. “Future work can consider additional relationship contexts, such as romantic partners. We are also interested in how peer influence intersects with other key socialising forces, including parents, who still play a meaningful role even as peers become increasingly important during adolescence.”