BackgroundWales spends more than £60 million per year on national public health improvement programmes, which currently are largely without a systematic evidence base or rationale. Economic evidence for public health programmes is sparse. However, it is essential to help inform policy and implementation. Owen and colleagues (2010) synthesised the evidence of 200 base-case cost-effectiveness estimates of evidence underpinning National Institute for Health and Clinical Excellence (NICE) public health guidance from 2006–10, because no comprehensive list of estimates was previously available. MethodsWe describe a national All Wales programme budgeting and marginal analysis (PBMA) analysis lead by Public Health Wales. We build on a mapping exercise of current Welsh Government-funded health improvement programmes, primarily delivered by the public sector, undertaken by Prof Sir Mansel Aylward. PBMA analysis offers a transparent and systematic way to examine policy goals, key stakeholders, and evidence of effectiveness, cost-effectiveness, and reach to disadvantaged groups. We discuss the practical challenge of promoting consultative buy-in by Directors of Public Health and their teams at the seven health boards across Wales, while managing necessary budgetary control and strategic planning at a national level. FindingsThe 31 programmes reviewed span infant and childhood programmes such as Designed to Smile (a programme to improve the dental health of infants and children in Wales), programmes for adolescents such as peer-led smoking cessation programmes (ASSIST), adulthood programmes such as smoking cessation services for example helplines and brief interventions, and the National Breastfeeding Programme, to programmes for older adults such as the National Exercise Referral Scheme. There is disparity between the funding of these programmes and the availability of clinical and cost-effectiveness data for each programme. We also noted that most programmes are weighted more towards the youth of Wales with a higher number of programmes aimed at pregnant mothers, infants, children, and adolescents. InterpretationThis PBMA exercise at a national All Wales level will map out current spending on health improvement and the full range of agencies and professionals currently delivering health improvement programmes, spanning the NHS, local government, schools, and the third sector. We will relate this budget to evidence of clinical and cost-effectiveness, the extent to which programmes match with stated Welsh Government health policy objectives and key themes, and the current and potential effect on reducing health inequalities. This search will also help to identify potential new opportunities for introduction or implementation through existing services of evidence-based health improvement programmes or interventions not currently funded or delivered in Wales. This is rational reinvestment in action. FundingNone.