Human behavior is greatly influenced by the social context. The currrent study on men’ and women’s cooperative behavior investigated the influence of long-term and short-term effects of socializing in group. The repeated Prisoner’s dilemma carried out in groups of 6 participants was used as the main experimental situation. The differences were found in changes in the level of cooperation, taking in to account the effects of mixing social and gender variables. Socialization made cooperation of group members strength and sustainable. However, men’ and women’s cooperative behavior in groups differed. Women were initially more inclined to cooperate in interaction with strangers. Men showed greater sensitivity to sociality effects. They tended to make cooperative decisions more often if there are friends in the group. Furthermore, men cooperated with previously unknown people after socializing with them significantly more than women