This paper examines whether changes in personality traits influenced life satisfaction (LS). This involved investigating whether these associations were moderated by age and mediated by hedonic balance (i.e., positive and negative affect). Participants included 11,104 Australian adults aged 18-79. years, with data available from two time points (baseline and 4-year follow up). Latent difference score modeling indicated that increased neuroticism was associated with lower LS, whereas increased extraversion, conscientiousness, and agreeableness were associated with higher LS. These relationships were moderated by age, and were less evident in older adults. Hedonic balance partially mediated the relationships between change in neuroticism and extraversion with LS. These findings provide important insights into longitudinal associations between personality change and LS.