Although howlers devote a small proportion of their time to socializing, social behaviors play an important role in the survival and reproduction of all individuals. The aim of this work was to analyze the spacing and social interactions among individuals of a group of Alouatta guariba clamitans with known relatedness for almost all individuals. Field data were gathered through 140 h of observation carried out over two years. Social interactions were just 1,4% of all activity. Infant play was the most frequent interaction and usually involved related immature individuals. Grooming was performed mainly by adult females over their offspring. Agonism and mating were rarely observed. The emigration of a juvenile and group fission were also reported. Adult females and its offspring exhibited great proximity. It seems that kinship may have an important role in the social structure of some howler groups.