績效評估（Performance Appraisal）是執行人事行政之一種重要工具，它係透過系統的方法、原理來評定和測量員工在職務上的工作行為和工作成果。它也是管理者與員工之間的一項管理溝通活動。無論組織大或小、企業、政府或教育成員之表現必須被評估，以作為俸級、陞遷、契約終止、訓練需求等組織重要計畫之決策參考。綜言之，績效評估之目標在於組織效能之強化，以達成批判性及發展性之雙重目的。本文所採用的研究方法為實地研究法，此研究方法係研究者以其專業素養，親赴擬探討之現象相關之場合進行體驗與觀察，就其經歷作為分析之資料，擬以驗證研究理論與假設。為進行本論文，筆者於本（九十三）年六月十四日至八月十三日期間赴美國洛杉磯郡，拜會該郡政府負責規劃全郡員工績效評估制度之主任行政局等機關，以實地瞭解績效評估架構及運作情形。本文研究目的在於瞭解美國洛杉磯郡政府績效評估制度所建構策略計畫（Strategic Plan）、績效次數架構（Performance Count）及個人績效評估（Performance Appraisal）等措施之實際作法。本文主旨為美國洛杉磯郡政府績效評估制度係由郡層級之策略計畫、局層級之績效次數架構及個人績效評估所構成由上至下層級，層層相關所型塑而成，為完成全郡政府設定之願景及任務所建構之績效評估體系，以及該體系對我國現行績效評估制度之啟示。 Performance Appraisal（PA） is an important tool of personnel administration. Its importance is because of the systematic approaches and theories to evaluate and measure the behavior and performance of employee. From the perspective of management, PA is also an indispensable communication process between the supervisor and employee. The performance of employee from various organizations evaluated in a period of time is the dependable sources in the decisions about pay upgrade, promotion and contract terminated. PA is indeed effective in strengthening the effectiveness of organization to fulfill its goal and achieve the judgmental and developmental purposes simultaneously. The research method applied in this thesis is the Field Research, which heavily depends on the researcher’s professional background while conducting research. Through the researcher’s actual observation and experiment, the collected information can be effectively analyzed to support the theories. This thesis takes two-month time for researcher to make it possible. During the two months, Office of Chief Administration and other government offices in County of Los Angeles are visited for collecting supportive information regarding the framework and operation of performance appraisal system of Los Angeles County. The main purpose of this thesis is to understand the “Strategic Plan ”, “Performance Count” and “Performance Evaluation”; these measures are systematically formulating the PA system of Los Angeles County. The main theme of this thesis is that the whole PA system is to fulfill the vision and mission set by Los Angeles County government under a close combination of the county-level strategic plan, the department-level performance count framework and the top-down performance evaluation, and how does this PA system mean to that of our nation.