Past research on materialism has focussed on adults and adolescents, with very little attention paid to younger children. In older populations, materialism has been linked to low self-esteem, increased aggression and delinquency, low prosocial behaviour and increased narcissism. This study aimed to identify whether these results could be replicated in pre-teen children, with particular attention paid to the impact of materialism-narcissism interactions on behavioural outcomes. Seventy-five children aged between 8 and 11 were assessed using child self-report measures of materialism and self-esteem, and teacher reported measures of relational and physical aggression, and narcissism. Results found that, unlike in previous studies of adults, materialism had no independent effects on adjustment variables. However, significant interactions with narcissism were identified indicating that children high in narcissism and high in materialism were particularly likely to be relationally aggressive. In contrast, high materialistic high narcissistic children were also far less likely to be physically aggressive. Results were discussed with reference to models of narcissism and materialism, and particular characteristics of the study sample. Suggestions for future research were considered.