Issue addressed: The SunSmart Policy Support and Intervention Study (SSPSIS) (ACTRN12614000926639) investigated the feasibility of improving schools’ implementation of the SunSmart Program, which is a resource for primary school communities to support their development of a comprehensive sun protection policy. Methods: A cluster randomised controlled trial (RCT) was used to evaluate the SSPSIS, which was conducted in NSW SunSmart schools (n = 20). Objective measurements of students’ sun-safe hat-wearing behaviours and sunscreen application, and teachers’ role-modelling behaviours, were collected for baseline, post-test and follow-up data. Interviews with school community stakeholders, including students (n = 103), parents (n = 31), teachers (n = 11) and executive staff (n = 4), were conducted to inform the intervention design, which was implemented following baseline data collection. Results: The results of baseline observations and interviews have been published previously. The intervention design aimed to combat negative perceptions of hat-wearing policy and create a trigger for sunscreen application by rewarding students practising these sun protection behaviours with play-based incentives. Although this intervention had no significant effect on the wearing of sun-safe hats among students or teachers, it did have a large effect on the consumption of sunscreen. Conclusions: Associating sunscreen and play-based incentives can create an effective trigger for students’ sunscreen application behaviours. However, further evidence is needed to investigate how students’ and teacher role models’ hat-wearing behaviours could be increased. So what?: While combining a play-based incentive with a trigger for behaviour can promptly increase students’ sunscreen application, it was unable to increase students’ or teacher role models’ hat-wearing behaviours.