Practitioners who work with children and young people such as educators, psychologists, and social workers, are required to understand and respond to various sexual behaviours in children and young people. However, there is a dearth of training programmes dealing with sexual development. To reduce over- and under-reporting of risk, which can have serious adverse outcomes, it is essential to educate practitioners in understanding and responding appropriately to sexual behaviours. This study evaluated Traffic Lights® professional development training programme – a one-day programme offered across Queensland, Australia, with the goal of educating practitioners and promoting safe and respectful sexual health among children and young people. Thirty postgraduate psychology students working with/interested in working with children and young people received Traffic Lights® training, and accuracy of understanding and responding to sexual behaviours presented in scenarios was assessed pre- and post-training. Participant responses were scored using criteria developed by a local sexual health organisation’s research specialists. Findings revealed no significant improvement in understanding and responding to sexual behaviours in children and young people. Implications of this study include recommendations for small-scale evaluations with sexual health experts and follow-up research, which is critical given the need for evidence-based practice in this area.