Several issues of current debate in health promotion evaluation are examined. These include the definition and measurement of relevant outcomes to health promotion, and the use of evaluation methodologies which assess both the outcome achieved and the process by which it is achieved. Considerable progress is being made in understanding the complexity of health promotion activity, and in the corresponding need for sophisticated measures and evaluation research designs which reflect this complexity. The more powerful forms of health promotion action are those which are long term, and least easily predicted, controlled and measured by conventional means. Against this, important and valued advances in knowledge and credibility have come from more tightly defined and controlled interventions, which have been evaluated through the application of more traditional experimental designs. This tension between ‘scientific rigour’ and the perceived advantages (in longterm effectiveness and maintenance) coming from the less-well-defined content and methods of community controlled programmes continues to pose technical problems in evaluation. It is important to foster and develop evaluation designs which combine the advantages of different research methodologies, quantitative with qualitative, in ways which are relevant to the stage of development of a programme. The use of a diverse range of data and information sources will generally provide more illuminating, relevant and sensitive evidence of effects than a single ‘definitive’ study. Evaluations have to be tailored to suit the activity and circumstances of individual programmes—no single methodology is right for all programmes.