Immunization is a public health area in which the intergovernmental challenges of formulating a national policy are evident. It is also an area in which harmonization of policy across Canada is particularly critical. The National Immunization Strategy was a F/P/T initiative designed to achieve this policy goal. The combination of national guidelines and flexible federal funding via a trust has, to date, been effective in improving equality of access to vaccines in provincial/territorial programmes with limited intergovernmental discord. The long-term success of the initiative will, however, largely depend on ongoing federal financial support and provincial/territorial views on national guidelines. This approach to immunization is a model that would lend itself well to other public health areas in which there is large variability in provincial/territorial programmes, where uniformity of programmes is particularly important and where there is a reluctance or inability of the federal government to legislatively mandate the harmonization of programmes.