近年在全球新公共管理運動下，政府採用契約委外的市場化方式，欲藉由私部門組織之間的競爭，以提升公共服務的績效。本文採用委託人－代理人理論作為分析途徑，根據台灣地方社會服務契約委外的公共管理方與民間簽約方，對於簽約過程與簽約結果的觀感，發展出以下論述：地方社福行政機關採用契約委外的主要理由，並非是經由實質性競爭而提高績效，而是配合政府再造的精簡人力員額而採取的政策工具，而且可以藉由社福型非營利組織所經營的關係網絡，爭取其支持以擴大政策層面的影響力；社福型非營利組織承接地方社會服務契約也同樣不希望面臨實質性競爭，而是期望在特定的地方社會服務領域之內，利用公共資源與權威，連結更多的民間組織與受益民眾，深化組織的使命以擴大社會層面的影響力。因此，在公共服務契約委外的績效之中，地方社福行政機關較重視節省人力成本的經濟指標，以及反映社會成本與產出之間比例的效率指標；相對而言，社福型非營利組織較著重提高受益民眾滿意程度的品質指標，以及政策目標的實現程度的效能指標。 With the global movement in New Public Management, the Taiwanese government is adopting the market outsourcing method of contracting out in the hope of using such types of competition in the private sector to improve its public service performance. This study employs the principal-agent theory to analyze the characteristics of local social services and the institutional environment, such as the main reason that local social welfare administrative agencies contract out services is not because of improved performance as a result of material competitiveness, but because of governmental policy to streamline human resources. In addition, through the relational network offered by social welfare nonprofit organizations, the government can gain support and expand its influence on the policy level. Likewise, social welfare nonprofit organizations undertake contracts with local social services to avoid material competitiveness in a particular field. They hope to take advantage of public resources and their authority to increase their connection with a greater number of private organizations and public recipients, thereby furthering their mission and expanding their influence in society. Therefore, in terms of the performance of contracting out public services, social welfare administrative agencies emphasize the efficiency ratio between the economy of labor, and the social cost and output while social welfare nonprofit organizations emphasize the increase in the quality index of public satisfaction and the effectiveness index of fulfilling policy objectives.