Engagement in hand-held phone use while driving is a prevalent issue among young drivers. Therefore, it is important to identify contributors to the behaviour. Social Norm Theory suggests that the perceptions of others’ approval of, and engagement in, a behaviour can influence one’s own engagement in the same behaviour. These perceptions can result in increased engagement in risky behaviours if they are over- or under- estimated. The current study implemented a mixed-method design to explore young drivers’ perceptions regarding their peers’/friends’ approval of, and engagement in, hand-held phone use while driving, and to identify the relative influence of perceived social norms on hand-held phone use while driving among young drivers. Overall, 510 young drivers completed a survey and 30 young drivers participated in interviews. Surveys and interviews questioned participants opinions on their own and others (peers and friends) approval of, and engagement in, hand-held phone use while driving. Quantitative results indicated that young drivers believe others approve of, and engage in, hand-held phone use while driving more than themselves. Perceived social norms significantly predicted increasing engagement in hand-held phone use while driving, however the magnitude of the effects were very small. Qualitative data provided a richer understanding of the topic, suggesting that the effects may be larger in certain groups who are particularly influenced by their peers/friends. Implications for future research are discussed with particular focus on exploring the use of a social norm approach in realigning perceptions of others approval of, and engagement in, hand-held phone use while driving.