Two forms of unwritten contracts derive from relations between organizations and their members. Psychological contracts are individual beliefs in a reciprocal obligation between the individual and the organization. Implied contracts are mutual obligations characterizing interactions existing at the level of the relationship (e.g., dyadic, interunit). Employee/employer relations and changing conditions of employment give rise to issues not addressed in conventional transaction-oriented models of motivation and individual responses. The development, maintenance, and violation of psychological and implied contracts are described along with their organizational implications.