公共行政学（Public Administration）简称为行政学，主要结合政治学和管理学为其理论基础。简言之，公共行政即是公务的推行、政府的管理，举凡政府机关或公务机构的业务，如何使之有效的加以推行，即是公共行政，这是最广义的解释。其关注重点在于如何透过政府在最有效地运用资源的情况下，为社会提供最具效益、最适切、且最合理的公共服务。有别于政治学，公共行政学者比较关注资源分配、社会公义、经济效益等议题，而政治学者则比较着重权力分配与取得、国际关系等议题。

负责推行公共行政而有直接隶属于各级政府的受薪人员通常称为公务员。在发展得较为成熟的政府体制中，公务员通常会秉承政治中立的原则，按照上级公务员或由具民意基础产生的政治家的指示运行政府的政策。在后者情况下，具民意基础的政治家一般拥有主导政府政策方向的权力，但同时须就政策的成败负起政治责任。

Public administration is the implementation of government policy and also an academic discipline that studies this implementation and prepares civil servants for working in the public service. As a "field of inquiry with a diverse scope" its "fundamental goal... is to advance management and policies so that government can function." Some of the various definitions which have been offered for the term are: "the management of public programs"; the "translation of politics into the reality that citizens see every day"; and "the study of government decision making, the analysis of the policies themselves, the various inputs that have produced them, and the inputs necessary to produce alternative policies."