The aim of this thesis is to contribute to existing knowledge. If the knowledge is not useful in building society it has limited value. In order to be a tool for decision-makers, Preventive Home Visits (PHVs) are described and discussed according to a realist synthesis approach. The premise of this approach is that a single trial cannot tell the whole story and that understanding theoutcome pattern is much more important than seeking regularities in results across different trials. In order to understand the o utcome pattern, the PHV strategy in Nordmaling is examined against other trials and scientific work, and also in grey literature such as reports and workingpapers. An increasing population of seniors means that resources for health and elderly care are being scrutinised in order to achieve the best possible health for the money invested. PHVs represent one strategy that attempts to promote health among independent seniors. This thesis is a multidisciplinary study aiming to gain knowledge about the effects of PHVs and to understand the mechanisms of importance when implementing this particular strategy. The point of departure is a study conducted in Nordmaling in the north of Sweden among healthy seniors aged 75 years and over. The study, conducted as a controlled trial during 2000 and 2001, showed a decrease in mortality as well as the utilisation of care, and an improvement in indicators of perceived health. Cost analyses showed significant savings for the municipality following a reduction in the use of home help. These and other savings combined with costs of the intervention were related to saved life years and used to conduct health economic analyses. Medical and social records from the primary health centre and the municipality, along with official registers provided information for modelling health economic analyses from a lifetime perspective. Results showed that the costs of PHVs were less than 10 000 Euros per gained life year, against an acceptable level of cost effectiveness of 50 000 Euros. Using a shorter time perspective, the result was even more favourable for PHVs. It was evident that the time window used in the analyses, the normative choice of including future healthcare costs or not, and how to handle the value of the seniors’ production were important factors in determining the results. Two years after the trial, in-depth interviews were conducted with 5 seniors who had experienced PHVs, in order to gain understanding of the outcome of the PHV trial in Nordmaling. Participants were selected with respect to their health and how they responded to advice given during the PHV trial. Grounded Theory was used to analyse the interviews. Seniors who used autonomous coping strategies in everyday life gained less from PHVs than other seniors. All participants could benefit from PHVs, but in order for these to be successful it was important for the home visitor to be professional and to understand how the different coping strategies of seniors worked. Taken together, the different aspects of this study raised normative questions that are discussed in this thesis. One, whether the production of seniors has any monetary value in health economic analyses conducted from a societal perspective, was addressed in a smaller diary study where 23 seniors were asked to keep a diary in order to identify everything they did over a oneweek period. It was evident that most of the respondents “produced” a lot, however the production of seniors is rarely taken into account in health economic analyses. The concept of “senior production” includes both the market value of what seniors do, as well as the value of what society can avoid doing if the seniors are independent and healthy.