This paper examines four themes in public health theory and practice: all are important for the future and are illuminated by the last 125 years. First, while definitions of public health may be stable, the rationale of public health practice--'why bother?'--has altered considerably over time. A second theme revolves around personal autonomy--can we compel individuals to take health promoting measures? Third, public health practice today pays attention as never before to the use of research-based evidence, helping to answer three questions: What are the problems? What are their causes? What are the solutions? The fourth theme is the changing character, locus and focus of public health. From being predominantly locally focused within Borough Councils, albeit operating within frameworks of national legislation and one eye on global threats, it has become much more complex with emerging levels of action which encompass the neighbourhood, the strategic district, the region, nation state, Europe and finally the ever more pressing globalisation agenda as it affects the human condition. Public health has been medically dominated for the last 125 years and this is now changing. Its ties with local government are being strengthened after a break of nearly 30 years. The focus of public health has recently been strongly on health services. This reached its apogee a few years ago but is also now rapidly changing. Looking back over the last 125 years can help us identify some of the mistakes to be avoided and opportunities to be seized at this time of change.