Despite the rise in childhood obesity, there remains a paucity of evidence for effective interventions that engage children and parents sufficiently to make and sustain lifestyle behaviour change. The Healthy Lifestyles Programme (HeLP) is a school-located obesity prevention programme, which has been developed with teachers, families and healthcare professionals. The underpinning assumption in the development of HeLP was to take a relational approach to changing behaviour, building relationships with the schools, children and their families to create supportive environments for healthy lifestyle choices. Thus, HeLP was conceptualised as a complex intervention within a complex system and developed as a dynamic, evolving set of processes to support and motivate children towards healthy behaviours. The delivery methods used are highly interactive and encourage identification with and ownership of the healthy lifestyle messages so that the children are motivated to take them home to their parents and effect change within the family. We have good evidence that HeLP engages schools and children such that they want to participate in the Programme. Results from an exploratory trial showed that the Programme is feasible and acceptable and has the potential to change behaviours and affect weight status. This paper presents an overview of and recommendations arising from the conceptualization; development and evaluation of the Healthy Lifestyles Programme as part of a special issue focusing on novel approaches to the global problem of childhood obesity.