Hand dominance has been studied by many researchers, however contradictory findings still exist as to whether preferred hand dominance increases with age or do we become more ambidextrous. Recently Gooderham and Bryden (2013) showed that perhaps there is a third option, that there is no increase or decrease in laterality but rather preferred motor dominance remains consistent throughout adulthood. Another related finding is that females appear to have an advantage in some handedness tasks, such as the Grooved Pegboard (e.g., Ruff & Parker, 1993), while when a larger pegboard is used, sex differences may reverse as males may perform better (Peters & Campagnaro, 1996). Further, sex differences disappeared when differences in hand size were accounted for. While sex differences are apparent in pegboard performance, it is not fully understood if these sex differences arise from an early age and continue throughout life. Therefore we sought to explore sex differences in preferred hand dominance throughout the lifespan by testing 191 participants (27 females and 32 males aged 8 and under; 15 females and; 9 males between the ages of 8-12; 35 females and 36 males between the ages of 18-30; and 20 females and 17 males between the ages of 60-85) using a standard size and modified Grooved pegboard (larger pegboard). Our results showed a preferred hand advantage in the youngest and the oldest age group, but not with older children or with adults. As well, when hand size was used as a covariate, sex differences disappear for younger and older adults. Furthermore younger children, adults, and older adults all showed an advantage in using the larger pegboard, but the advantage was not evident for older children. Therefore, our data support the notion that the preferred hand advantage increases with age and that sex differences may be explained by hand size.