The primary assertion of the Socioemotional Selectivity Theory (SST) is that with increasing age, individuals become more selective in their social networks and consciously reduce their social network size. Although SST has received considerable support from studies conducted in mostly individualistic countries, such as the United States and Germany, there are very few studies in which it has been tested in collectivistic countries. Therefore, the present study aimed to test the SST argument in Turkey. There were 219 Turkish young adult participants, aged 18–28 (Mage = 20.07 years, SD = 1.76). Participants completed a Social Convoy Questionnaire, Future Time Perspective (FTP) scale and Positive and Negative Affect Schedule. Via the structural equation model, it was found that (a) open-ended FTP directly and positively related to positive affect, higher level of social satisfaction, and smaller social network sizes; and (b) social satisfaction mediated the relationship between FTP and young adults’ positive affect. The results confirm the SST’s arguments and highlight the importance of social satisfaction in helping shape young adults’ positive affect.