The article focuses on ways in which third-party liability requirements generate a complex system of exchange relations and dependence between the INS and international airlines, a system that affects in important ways how the INS handles cases of suspected inadmissible travelers. The study of immigration inspection work took place at a large international airport. Discretionary decision-making at the secondary inspection stage when questions arose about a person's admissibility to the United States involved observations and interviews over a 102-day period. About 1,600 foreign nationals were inspected daily, of which about 35 to 40 received secondary inspection and only 1 or 2 were found inadmissible and returned. A high priority of inspectors and supervisors was avoiding the overnight detention of inadmissible travelers, and this priority imposed constraints on inspectors. To avoid detentions, inspectors worked within practical contingencies of return flights and flight schedules. Findings suggested official behavior was shaped not by direct pressures from the airline industry but more indirectly by specific agency constraints that established practical work concerns and conditions and that increased the dependence of inspectors on the cooperation and goodwill of airline personnel. Agency officials became enmeshed in exchange relations with airline personnel in which both came to expect quid pro quo exchanges and through which each acknowledged certain special interests and concerns of the other. It was determined government use of private enterprise in enforcement can sometimes have unintended consequences. Rather than simply an enforcement strategy being introduced into a particular setting, third-party liability can become entwined with the organizational circumstances of officials and result in mutual dependence and exchange between public and private entities. 42 references and 11 footnotes