This paper is an attempt to make some links between the dynamics of large groups as manifested in group relations events and their less manifest presence in organizations. Turquet's concept of Basic Assumption Oneness is understood as a defence against annihilation anxiety in large group settings. I am suggesting that annihilation anxiety is present in organizations, particularly those facing threats to their existence either from external pressures or (in the case of therapeutic communities) from the powerful destructive force of primitive projective mechanisms. Although basic assumption oneness is less visible in organizations, it can be inferred from certain types of sub-system functioning. In particular, when an organization attempts to defend against feared annihilation by uniting in hostility towards a particular sub-group, the consultant must work with the organization as a whole to resolve profound underlying anxiety.