Schools can have good or bad influences on young people’s health and wellbeing. They are important settings for early intervention to prevent later physical and mental health problems. Effective prevention may reduce costs to health services later in life. Wales’ education system is currently undergoing major reform. From 2022, all schools will implement a new curriculum, which, for the first time, will place Health and Well-being at the centre of learning. An aim of the curriculum is that all children in Wales will be “healthy, confident individuals”. Health and wellbeing will become 1 of 6 Areas of Learning and Experience (AoLE) alongside Expressive Arts; Humanities; Languages; Literacy and Communication; Mathematics and Numeracy; and Science and Technology. School reform has the potential for widespread benefit to pupils, schools and wider society; however, it could also lead to unintended harms. This is why it is important that new policies, such as this one, are accompanied by good quality evaluations. This research provides a time limited opportunity to lay the foundations for a high quality evaluation of the impacts of the new curriculum on pupil health and wellbeing.