Rationale: Self-esteem is an adaptive personality factor that has been associated with good physical health. While research has observed that self-esteem and physical health typically decline in older adulthood, there is a paucity of research investigating the associations between changes in self-esteem and physical health across the adult lifespan.

Objective: The present study examined whether changes in selfesteem and chronic disease exert reciprocal effects on subsequent changes in self-esteem and disease. In addition, it investigated whether individuals' age would moderate these associations.

Methods: The study analyzed data from 14,117 adult (18+) Canadians who completed surveys over 16 years, from cycles 1 to 9 of the National Population Health Survey (NPHS). Self-esteem, chronic diseases, and demographic information were collected.

Results: Cross-lagged panel analyses indicated reciprocal age-related associations between changes in self-esteem and chronic disease. Initial decline in self-esteem predicted subsequent increases in chronic disease, and initial increases in chronic disease predicted subsequent declines in self-esteem, only among young adults, and not middle-aged or older adults.

Conclusion: These results suggest that age may qualify the associations between declines in self-esteem and physical health and that adverse changes in both factors may be particularly problematic for young adults' prospective personality functioning and physical health.