Nonprofit organizations face complex problems in managing resources on a continuing basis because their funding sources differ greatly in structure and predictability. Case studies of four nonprofit social service agencies, representing key theoretical dimensions from models of organizational behavior, show how the agencies relate to different funding sources and manage the challenges they present. Donations and government Junding vary in their predictability and in the scope of management work they demand; such funding contingencies impede strategic planning and can drain other organizational resources. Funding relationships involve gov ernment agencies and nonprofit organizations in a system of mutual dependence.