Set-point theory is the main research paradigm in the field of subjective well-being (SWB). It has been extended and refined for 30 years to take in new results. The central plank of the theory is that adult set-points do not change, except temporarily in the face of major life events. There was always some ‘discordant data’, including evidence that some events are so tragic (e.g. the death of one’s child) that people never regain their set-point. It was possible to dismiss these events as ‘exceptions’ and maintain the theory. However, several new findings are emerging, which cannot be dismissed as ‘exceptions’ and which appear to require substantial revisions or replacement of set-point theory. Many of these findings are based on the German Socio-Economic Panel Survey (SOEP 1984-), which provides the longest available time series on life satisfaction. Despite its centrality, the concept of the set-point is often not precisely defined. In this paper three alternative working definitions are offered. Depending on which definition is used, it is found that over 20 years 14–30% of German panel members recorded large and apparently permanent changes in their set-points. Changes of this magnitude are not compatible with set-point theory as currently understood. The challenge for SWB researchers now is to develop a theory which can account for change as well as stability.