We tested the hypothesis that long-lived white-footed mice, Peromyscus leucopus, were phenotypically and behaviorally different from short-lived mice in a 7-year study of a population in northwestern Ohio. Of > 1,800 individuals captured, 2.3% remained in the population >345 days (20 males and 22 females). Post-weaning mortality was nearly constant, but autumn-born mice suffered higher early mortality than did spring-born mice. Females, but not males, had a better chance of reaching old age if they were born in autumn. Comparison of home-range size and body mass did not indicate phenotypic differences between long- and short-lived mice, and long- and short-lived females produced litters at the same rate.