A prevalent issue facing older adults is the increased risk of falling. It is estimated that between 30-60% of older adults will fall each year, having a detrimental impact on quality of life (Rubenstein, 2006). Ability to maintain postural stability is reliant on a complex and dynamic interaction between cognitive, motor, and sensory resources (Horak, 2006). The likelihood of falls or loss of everyday functionality can be attributed to the age-related decline in accuracy of the sensory integration process. Previous studies (Doumas & Krampe, 2010; Craig & Doumas, 2019) suggest that older adults show equally efficient adaptation to environments with inaccurate proprioceptive information about body sway as younger adults, however, de-adaptation seems to be impacted by age-related decline. This study aimed to replicate previously observed effects and explore their link to a common-mechanism of age-related decline in sensory processing. The present study predicted that older adults would demonstrate a longer aftereffect following a balance disturbance as well as take longer to detect the platform stopping. Participants included 45 young adults (YA) (aged 18-35, M = 17, F = 28) and 33 older adults (OA) (aged 70+, M = 15, F = 18). Baseline posture was assessed on a fixed platform with eyes closed for two minutes, followed by either a short adaptation (YA n = 23, OA n = 17) (condition (sway-referenced platform for one minute), or a long adaptation condition (YA n = 22, OA n = 16) (sway referenced platform for 6 minutes). This was concluded by a three minute reintegration phase on a fixed platform. Gain was set at 1.0 for older adults and 1.6 for young adults, aligning with research from Craig and Doumas (2019), to reflect differences in adaptation sway for the two age groups.  Participants were instructed to press a button when they perceived the platform had started or stopped. Data from all measures were analysed using mixed-design ANOVAs with group (Young, Older) and length (Short, Long) as between- and window as within-subjects factors. Postural sway path length was calculated using L5 position-time trajectories in the AP (anterior-posterior) direction. As predicted, results showed that aftereffects were more pronounced in the long adaptation condition for both age groups, and were greater for older adults. In addition, older adults experienced longer perceptual delay, however, in contrast to our predictions, no differences were found between older adult groups in the long and short condition. The findings suggest that older adults show an age-related decline in sensory re-weighting, as shown through greater aftereffects than younger adults after a long adaptation period. In addition, Older adults experience greater perceptual delay than their younger counterparts after a period of instability. However, robust links between greater perceptual delay and greater aftereffects require further study.