Three studies examine how the future prospects of new group members affect newcomer acceptance and newcomer influence. In Study 1, participants anticipate accepting temporary newcomers less easily than permanent newcomers because they expect temporary newcomers to differ from the group. In Study 2, the effects of newcomer entry in three-person groups are examined. Results show that groups perceived temporary newcomers as more involved in a judgmental decision-making process than permanent newcomers. In Study 3, a hidden profile task confirms that temporary newcomers indeed shared more unique knowledge during discussions than permanent newcomers and that this enhanced the groups' decision quality. However, compared to permanent newcomers, temporary newcomers caused teams to experience more conflict and less group identification, illustrating the tension between innovative group performance and group cohesion. The results are discussed in light of the social identity perspective and research on minority influence.