Worldwide, road trauma is the leading cause of death among young people.Young drivers aged 18 to 25 years are both more accepting of technology and more likely than any other age group to use a mobile phone while driving, particularly smartphones. Young drivers are also more likely to access the additional social interactive technologies available on smartphones, such as Facebook and email, placing them at increased risk of road trauma from driver distraction. Laws against mobile phone use while driving exist in some countries, such as Australia; however, they may not be having the same effect as the laws for other risky road user behaviours (e.g., drink-driving) as they are challenging to enforce. The development of other countermeasures such as public education messages, therefore, is critical to alert drivers of the risky nature of such activities.This program of research examined the role and effectiveness of public education messages that were developed and evaluated in accordance with the Step approach to Message Design and Testing (SatMDT). The SatMDT is a four step framework based on social psychological theory (i.e., the Theory of Planned Behaviour; the Elaboration Likelihood Model; the Extended Parallel process Model; and Social Learning Theory) and includes ongoing input from young drivers who and inform and test every step. These messages were aimed at reducing key behaviours relating to smartphone use; namely, initiating, monitoring/reading, and responding to social interactive technology among young drivers aged 17 to 25 years.There were three distinct studies in this program of research, with each study building purposefully on the results of the previous study. A mixed methods approach was utilised with some studies utilising both qualitative and quantitative v methods within separate study phases. Study 1 of the research program identified pre-existing characteristics associated with the target audience and comprised three distinct phases. Study 1A (N = 14) was a qualitative study that identified the extent and nature of young drivers' involvement in the behaviour. Study 1B (N = 26) was a qualitative study that identified underlying beliefs of the target audience regarding the target behaviours and Study 1C (N = 114) was a quantitative survey study that verified whether the beliefs elicited in Study 1B were representative of a broader population of young drivers. The analysis of Study 1C data identified three key beliefs that would be fundamental to challenge in public education messages. Specifically, they were 'believing you are a good driver would encourage'; 'slowmoving traffic would encourage'; and 'friends and peers would approve' of a young driver accessing social interactive technology on their smartphone.The main aim of Study 2 was to develop and pilot message content based on the results of Study 1 to ensure the message content conveyed the anticipated message.Guided by theoretical and empirical evidence and in accordance with the SatMDT, nine messages were developed in the ini...