The present research experimentally examines the ininfluence of groupidentity on trust behavior in an investment game. In one treatment,group identity is manipulated only through the creation of artificial(minimal) groups. In other treatments group members are additionallyrelated by outcome interdependence established in a prior public goodsgame. In moving from the standard investment game (where no groupidentity is prompted) to minimal group identity to two-dimensionalgroup identity, we nd no significant dierences in trust decisions.However, trust is signfiicantly positively correlated with contributiondecisions. This suggests that cooperative attitudes are idiosyncraticpreferences, which are not affected by the creation of an arbitrarygroup identity.