There are various social groups that we can meet in today's society. Within Taratara society, there is one social group called Serikat Mahmejaan. The aims of this study is to find cultural values and characteristics social changes in Serikat Mahmejaan of Tatatara Society. The research process was carried out in the village of Taratara, Tomohon-North Sulawesi. The method used in this study is descriptive qualitative, with purposive sampling research subjects, and data collection techniques with unstructured observation and semi-structured interviews, while the data analysis technique uses Grounded Teory analysis techniques. The results of the study show that: (1) cultural values can be found in aspects such as: membership systems, leadership systems, preparation, Untepan Lutu’s rules and punishment, (2) changes in social characteristics found in aspects such as: membership systems, food menu, and Sabuah equipment. There are five cultural values found in the Serikat Mahmejaan of Taratara society: (1) family values, (2) cooperation values, (3) unity values (4) deliberation/consensus values, and (5) religious values. While characteristics social changes within Serikat Mahmejaan are: (1) seen from the shape, changes are small and desired and planned, (2) seen from the causes, changes that occur due to the situation and changing community needs because of new thinking and touch with other cultures.