Lifetime fitness and its determinants are an important topic in the study of behavioural ecology and life-history evolution. Early life conditions comprise some of these determinants, warranting further investigation into their impact. In humans, for example, babies born lighter tend to have lower life expectancy and fewer offspring than heavier ones. Similarly, some of these life-history traits are passed on to offspring, with lighter-born females giving birth to lighter offspring. We investigated how weight at weaning, the relative timing of birth in the season, maternal weight, and maternal age affected the longevity and lifetime reproductive success (LRS) of female Columbian ground squirrels (Urocitellus columbianus). We hypothesized that early life conditions such as offspring weight would not only have lifetime fitness consequences but also intergenerational effects. We found that weight at weaning had a significant impact on longevity, with heavier individuals living longer. The relative timing of an individual’s birth did not have a significant association with either longevity or LRS. Individuals born to heavier mothers were found to have significantly higher LRS than those born to lighter mothers. Finally, maternal age was found to be significantly associated with their offspring’s LRS, with older mothers having less successful offspring. The latter finding may be due to an increased success of offspring reproductive success when their mother is still present. Our results provide evidence that early life conditions do have lifelong fitness and sometimes intergenerational consequences for Columbian ground squirrels. Keywords: maternal effects, longevity, lifetime reproductive success, early life conditions, Columbian ground squirrel.