A minority of patients consume the bulk of health services and/or the costs of care. This group provides a focus for a number of concerns related to health system sustainability, the appropriateness and effectiveness of care and the proportion of government program spending made up by health expenditures. This introduction offers five observations. First, if Ontario's Health Links are to meet the needs of high users, local autonomy may have to be balanced with more consistent frameworks. Second, there is a need for creative approaches to evaluation, specifically in the area of rapid cycle evaluation. Third, genuine innovation will require clear role specifications in governance relationships and bold approaches to accountability that build in space for learning from "good" failure. Fourth, successful interventions will encompass social care services and broader social determinants as well as clinical factors and, fifth, we will need an approach to stewardship that facilitates intersectoral action.