Voluntary agreements, mandates, and contracts integrate networks of social service organizations, allowing them to function as coordinated wholes. The author reviews the history of contracting and mandating in the public sector. It is hypothesized that contracted relationships formalize agreements between local organizations dependent on others. Mandated relationships are perceived to be important by policy-makers at a state or federal level. The differential acceptance and rejection of these relationships in the community is explored. Data from social service agencies are used to compare administrators' assessments of the effectiveness of mandated and contracted relationships used to coordinate a group of agencies delivering services to children. When a mandated relationship has been formalized into a contract by a local administrator the perceived effectiveness of that relationship is higher than any other relationship in the community. If the mandated relationship has not been formalized by a contract this relationship is perceived to be the least effective. Important mandated inter-organizational ties without monetary incentives are less likely to work. Local administrators having developed the contracted ties see these ties as producing a higher level of performance.