Bullying does occur in kindergarten, though it often looks different from the shoving-and-name-calling image most people associate with older schoolchildren. Research over the past two decades has established that aggressive behavior aimed at specific peers, repeated over time and involving a power imbalance, can emerge well before a child’s sixth birthday. Because young children are still building the social and emotional skills that govern how they interact with others, the dynamics of early bullying are tangled up with normal developmental conflict in ways that make it easy to dismiss or overlook.
What Bullying Looks Like at This Age
Adults tend to picture bullying as something that happens in middle school hallways, so it can be jarring to hear the word used for four- and five-year-olds. The behaviors are real, but they skew heavily physical in the earliest years. A large study of children aged one through five in Norwegian childcare centers found that more than half of two-year-olds used physical aggression at least a few times a month. As children reached age three and beyond, physical aggression started to decline while verbal and relational aggression, like excluding a peer from play or saying hurtful things, either increased or held steady.1International Journal of Bullying Prevention. Prevalence of Aggressive Acts Among 1- to 5-Year-Olds in Norwegian Early Childhood Education and Care That shift matters for kindergarten specifically: five-year-olds are landing right in the transition zone where hitting and pushing are tapering off but social manipulation is ramping up.
Not all aggression is bullying, of course. A two-year-old grabbing a toy is usually impulsive and indiscriminate. Bullying, even at young ages, involves targeting particular children repeatedly. One observational study of preschool aggression found that although most aggressive acts were physical, the kind of organized peer reactions familiar from school-age bullying research, where bystanders consistently defend or encourage, happened only rarely among the youngest children.2Developmental Neurorehabilitation. Peer reactions to early childhood aggression in a preschool setting: Defenders, encouragers, or neutral bystander In other words, the social infrastructure of bullying, with its clearly defined roles, is still forming in kindergarten. That makes it harder for adults to recognize what is happening, because it does not yet look like the classic schoolyard scenario.
Gender Differences in How It Shows Up
There is a consistent pattern in the research: boys are more likely to use physical aggression and girls are more likely to use relational aggression, though the relational side of the picture is messier than the physical one. A cross-national study spanning nine countries found that boys reported higher physical aggression in every country studied, but no consistent gender gap appeared for relational aggression.3PubMed Central. Boys’ and Girls’ Relational and Physical Aggression in Nine Countries In contrast, a longitudinal study focused specifically on preschool found that girls did show higher relational aggression than boys, and that children tended to direct aggressive behavior at same-sex peers.4Journal of Applied Developmental Psychology. A longitudinal study of relational and physical aggression in preschool
The disagreement probably reflects how hard relational aggression is to measure in very young children. Excluding someone from a game or whispering “you can’t play with us” is subtler than hitting, and it depends on the observer and the method. What is clear is that by kindergarten, both forms are in play. A study tracking aggression trajectories across early childhood found that when children entered a new classroom, both physical and relational aggression initially dropped, then crept back up as children settled in. The rebound in physical aggression was significant only for boys.5PubMed Central. Trajectories of physical and relational aggression across early childhood: Relations with peer risk factors For parents and teachers, this means the first weeks of a new kindergarten year may look deceptively calm before patterns re-emerge.
Why Some Young Children Bully
Young children who bully are not simply “mean kids.” A few developmental factors converge to raise the risk. Inhibitory control, the ability to stop yourself before acting on an impulse, and delay of gratification are among the strongest cognitive predictors of physical aggression in early childhood. Children who struggle with these executive-function skills are more likely to lash out physically, though these same skills do not predict relational aggression, suggesting that social exclusion and verbal cruelty tap into a different set of abilities.6Social Development. Executive function and theory of mind as predictors of aggressive and prosocial behavior and peer acceptance in early childhood Theory of mind, the capacity to understand what someone else is thinking or feeling, also predicted physical aggression in the same study. That may sound counterintuitive: you might expect children who understand others’ feelings to be nicer. But theory of mind can cut both ways. A child who understands that a peer feels scared or powerless can use that knowledge to dominate just as easily as to comfort.
Family life plays a role too, though not always in the ways parents fear. A longitudinal study comparing children with and without behavioral problems found that one parenting factor stood out: support for child autonomy. Children whose parents encouraged independent decision-making around ages four and five showed a steeper decline in bullying over time, regardless of whether the child had a diagnosed behavioral condition. Interestingly, the study found no longitudinal link between parental negativity or emotional warmth and later bullying.7PubMed Central. Parenting style influences bullying: A longitudinal study comparing children with and without behavioural problems That is a reassuring finding for parents who worry that every moment of frustration or imperfect warmth is setting their child up to be a bully. The evidence points more toward whether children are learning to navigate choices on their own than toward the emotional temperature of the household.
Siblings also matter. A study following children from toddlerhood found that sustained or escalating antisocial behavior toward siblings, things like consistently taking toys by force or refusing to cooperate, predicted bullying of unfamiliar peers later on, even after accounting for how the child was behaving toward siblings at the time of testing.8PubMed. Trajectories of antisocial behaviour towards siblings predict antisocial behaviour towards peers Sibling relationships, in other words, can function as a rehearsal space. A child who learns that aggression works at home may carry that strategy into the classroom.
Which Children Are Most at Risk of Being Bullied
While any child can be targeted, children with developmental or behavioral differences face dramatically higher odds. A population-based study found that every group of children with developmental or behavioral difficulties had elevated risk of peer victimization compared to typically developing children. The disparities were stark. Children with autistic traits faced the highest observed risk, roughly thirteen times the odds of being victimized compared to their typically developing peers. Children with emotional difficulties and behavioral difficulties also faced very high risk, at roughly eight to nine times the odds.9Journal of Pediatric Psychology. Peer-Victimization of Young Children With Developmental and Behavioral Difficulties—A Population-Based Study
These numbers are worth pausing on. The children most likely to be targeted are also the ones who may have the hardest time reporting what is happening or advocating for themselves. A kindergartner with language difficulties, who faced roughly four times the odds of victimization in the same study, may not have the verbal tools to tell a teacher “she keeps saying I can’t play.” A child with attention difficulties may be seen as disruptive by adults and overlooked as a victim. For parents of children with any kind of developmental difference, this research suggests that proactive conversations with teachers at the start of kindergarten are worth having, before problems surface.
How Early Bullying Affects Children
The effects of being bullied in the early school years are not trivial, and they are not things children simply grow out of. Research has found that victimization is a precursor to loneliness and school avoidance, not just a side effect of kids who were already struggling. Loneliness tended to be most pronounced while the bullying was actively occurring, but school avoidance showed a delayed effect, emerging after the victimization had been going on for a while. The longer the victimization lasted, the worse the adjustment problems became.10PubMed. Peer victimization: cause or consequence of school maladjustment? For a five- or six-year-old, avoidance can look like stomachaches on school mornings, crying at drop-off, or a sudden loss of enthusiasm for a place they used to enjoy.
The effects also show up in the body. Studies in children have consistently found that those who are bullied show altered cortisol patterns, the hormone most closely associated with the stress response. Bullied children showed both higher cortisol reactivity to a stressful task and higher total cortisol over the course of the task compared to children who had not been bullied.11PubMed. Bullying Victimization Heightens Cortisol Response to Psychosocial Stress in Chinese Children Chronic elevation of cortisol, measured through hair samples that capture months of exposure, has been linked to poorer executive function in preadolescents involved in bullying.12PubMed. Hair cortisol as a biomarker of chronic stress in preadolescents: influence of school context and bullying One study found that in boys who were victims, cortisol mediated the relationship between bullying and increased body fat, suggesting that the stress of being bullied can ripple into physical health outcomes.13PubMed Central. Does cortisol mediate the association between school bullying and weight status in preadolescents? These physiological findings are mostly from children somewhat older than kindergartners, but they illustrate why early intervention matters: the stress of sustained victimization is not just emotional. It reshapes how a child’s body responds to the world.
The Classroom Feedback Loop
Teachers are not passive bystanders in how kindergarten aggression plays out. A three-wave longitudinal study found a transactional cycle: children’s aggressive behavior at the start of kindergarten led to increased conflict with their teacher by midyear, and that heightened teacher-child conflict in turn predicted more aggressive behavior by the end of the year.14Journal of Clinical Child & Adolescent Psychology. Reciprocal relations between teacher-child conflict and aggressive behavior in kindergarten: a three-wave longitudinal study This is a feedback loop, not a one-way street. A child who acts out gets a more strained relationship with the teacher, which makes the child act out more. For teachers, recognizing this dynamic is the first step toward breaking it. Responding to aggression with warmth and structure rather than frustration and escalation is easier said than done, especially in an overcrowded classroom, but the research suggests it is one of the few levers adults actually control.
This finding also highlights a broader issue: kindergarten classrooms are often the first institutional environment a child navigates, and the quality of adult-child relationships in that setting can amplify or dampen aggressive tendencies. A child who enters kindergarten with poor impulse control but lands in a classroom with a patient, attuned teacher may not develop a bullying pattern. A child with the same impulse-control issues whose teacher responds to disruption with conflict may end up on a worse trajectory.
Do Prevention Programs Work
The honest answer is that the evidence for structured prevention programs in early childhood is mixed, and the programs that exist tend to work on skills that are adjacent to bullying rather than on bullying itself. An evaluation of a social and emotional learning program for kindergarten and primary school children in Poland found no significant reduction in physical, verbal, or relational aggression among children who participated, compared to a control group. The effects on aggression were described as too weak to be practically meaningful. The program did, however, improve children’s ability to recognize, name, and regulate their own emotions and to identify emotions in peers.15Scientific Reports. An evaluation of social and emotional learning-based program for kindergarten and primary schools in Poland
That result captures a pattern across many SEL programs aimed at young children: they reliably build emotional vocabulary and awareness, but the leap from “I can name what I’m feeling” to “I will stop pushing that kid” is a big one, and structured curricula alone do not always bridge it. This does not mean the programs are useless. Emotional recognition is a building block. But parents and schools should not expect that a semester of circle-time lessons will eliminate aggressive behavior. The factors that drive kindergarten bullying, impulsive temperament, family dynamics, peer group composition, teacher-child relationships, are too varied for any single program to address.
What Happens Over Time
One of the most concerning findings in the research involves children who are both aggressive and victimized, sometimes called aggressive victims. A study tracking children from first grade through the adolescent transition found that most children identified as aggressive victims in first grade continued to be significantly involved in bullying throughout elementary school. Those with recurrent aggressive-victim status showed higher levels of some mental health problems and greater school impairments as they entered adolescence, compared to children in other peer-status groups.16PubMed Central. Stability of early identified aggressive victim status in elementary school and associations with later mental health problems and functional impairments The stability of this role is the troubling part. Being caught in a cycle of bullying others and being bullied oneself at age six or seven is not a phase that most of these children simply outgrow. It becomes a stable pattern with worsening consequences.
This long-term trajectory underscores why waiting to see if a child “grows out of it” can be a risky strategy. The children who are most deeply entrenched in bullying dynamics in the early grades are the ones who are least likely to spontaneously exit those dynamics on their own. Early identification, before kindergarten roles harden, gives children and adults the best chance at redirecting the pattern.
What Parents and Teachers Can Actually Do
Given that formal programs have limited direct impact on aggression, the practical question becomes: what does help? The research points toward a few concrete strategies, none of them flashy but all grounded in evidence.
Supporting autonomy at home is one. As the parenting study described earlier found, children whose parents encouraged independent decision-making around ages four and five showed steeper declines in bullying behavior.17PubMed Central. Parenting style influences bullying: A longitudinal study comparing children with and without behavioural problems In practice, this means offering choices (“Do you want to wear the blue shirt or the red one?”), allowing children to solve low-stakes problems before stepping in, and resisting the urge to manage every social interaction for them. Children who practice making decisions and handling small conflicts at home arrive at school better equipped to navigate peer dynamics without resorting to aggression or collapsing in the face of it.
Monitoring sibling relationships is another underappreciated lever. Since aggressive patterns practiced with siblings can transfer to peers, parents who notice escalating hostility between siblings should treat it as a signal worth addressing rather than a normal part of childhood.18PubMed. Trajectories of antisocial behaviour towards siblings predict antisocial behaviour towards peers
For teachers, the feedback-loop research suggests that investing in the relationship with a difficult child early in the year, before conflict accumulates, may be the single most impactful thing they can do. This is not about tolerating aggression. It is about responding to aggression without allowing the adult-child relationship to deteriorate, because that deterioration feeds the very behavior the teacher wants to stop.
For children with developmental differences, proactive communication between parents and teachers matters. A kindergartner with autistic traits or attention difficulties is at sharply elevated risk of victimization, and the adults in the room need to be watching for it from day one rather than waiting for the child to report it.19Journal of Pediatric Psychology. Peer-Victimization of Young Children With Developmental and Behavioral Difficulties—A Population-Based Study Many of these children will not report it, either because they lack the language or because they do not fully understand what is happening to them.
The Limits of the “Bystander” Model in Young Children
Anti-bullying programs for older children often focus on empowering bystanders to intervene, on the theory that peer pressure is the engine that sustains bullying. That model does not map neatly onto kindergarten. Observational research found that the defender, encourager, and bystander roles described in the school-age bullying literature occurred very infrequently among preschoolers watching aggression play out.20Developmental Neurorehabilitation. Peer reactions to early childhood aggression in a preschool setting: Defenders, encouragers, or neutral bystander Young children are still developing the social cognition needed to take on these roles. They may not yet understand that their reaction to an aggressive act matters, or they may simply lack the confidence or skill to intervene.
This means that in kindergarten, the burden of intervention falls almost entirely on adults. Expecting five-year-olds to stand up for a victimized peer is unrealistic for most children at this stage. Teachers need to be present and attentive during unstructured times like recess and free play, when aggression is most likely to occur, rather than relying on children to self-police. Building bystander skills remains a worthy long-term goal, but in kindergarten, the adults are the bystanders who matter most.