The behavior of adult Tupaia glis was studied in Puerto Rico in a variety of cages and enclosures, in mixed groups of up to 8 individuals. A variety of social acts was identified and interpreted, including 5 vocal signals, 9 visual signals, 2 olfactory patterns, and 6 contact patterns. An analysis of 169 hostile episodes showed that dominant individuals were relatively quiet and engaged in more direct contact, while sub-ordinant ones were more vocal and tended to avoid contact. Neither sex was consistently dominant, but residents were usually dominant over intruders. Forty-four heterosexual and 22 homosexual episodes were analysed; only females participated in the latter.