Dominant-subordinate relationships in the Formosan squirrel, Callosciurus erythraeus thaiwanensis , were studied in the woods of Kamakura City, Kanagawa Prefecture, Japan from April 1982 to May 1985. Home ranges of adults overlapped, but the extent of overlap was less among females than among males. The mean number of squirrels with overlapping home ranges was 12.6 among males and 2.3 among females in the winter-spring season, and 8.7 among males and 1.6 among females in the autumn-winter season. When a squirrel encountered another, chasing occurred only once in three times; indifference was exhibited in most cases of proximity between individuals. A dominance hierarchy was apparent at a feeding stand in the study site. This hierarchy included both sexes and was correlated with age. The dominance hierarchy detected among males at the feeding stand reappeared in mating bouts. In a mating bout, nine-seventeen males assembled near an estrous female and four-eleven males successively mated in accordance with their rank. Compared to northern species in which dominant males guard the estrous female against lower-ranked males, in the Formosan squirrel, successfully mated males guarded the female for less than 70 min from the other males regardless of their rank. However, high ranking males mated with more females per year than low ranking males. This difference among species may relate to the number of males assembled for mating and the frequencies of mating bouts.