The capacity to measure change is essential in examining successful adaptation to ageing. Few studies measuring change have compared findings using pre-post approaches (employing difference scores) with those from retrospective approaches (employing self-ratings). Where this has occurred, differences have been attributed either to ceiling and floor effects or to the operation of social comparison (Choi, 2002, 2003). Our study compared pre-post and retrospective measures of change in health, health behaviors, and wellbeing over periods of 1 and 3 years among retirees. Retrospective measures were found to be more positive than pre-post measures. This discrepancy was associated with floor and ceiling effects and with a robust self-image, but not with recency, social comparison, or social desirability response sets. Pre-post difference scores have limitations as indicators of change, particularly where ceiling effects operate. A retrospective perception of improvement, combined with deterioration in scores, may result from successful psychological adaptation as people grow older. (Contains 5 tables.)