Public Administration, as a field of study, has evolved significantly over time. The classical theory of administration, which dominated the early 20th century, was largely influenced by scholars like Max Weber, Frederick Taylor, and Henri Fayol. Weber's theory of bureaucracy emphasized a formal hierarchical structure, rules-based operation, and a division of labor to achieve efficiency and effectiveness in organizations. Taylor, on the other hand, advocated for scientific management, focusing on increasing productivity through time studies and specialized work techniques.

In the 1940s, the human relations approach, pioneered by Elton Mayo, shifted the focus from structure and efficiency to human behavior and the role of interpersonal relationships in organizations. This school of thought argued that employee satisfaction and social factors within the workplace significantly influenced productivity.

The post-World War II era saw the rise of the New Public Administration (NPA) movement in the 1960s and 1970s. NPA emphasized social equity, ethics, and the public interest in administrative processes. It argued that administrators should be proactive in addressing issues like inequality and ensuring that public services benefit all citizens equitably.

In recent times, the concept of New Public Management (NPM) has gained prominence. NPM seeks to make public administration more efficient by incorporating private sector practices, such as performance measurement, decentralization, and a focus on customer service. It represents a shift towards making government institutions more business-like in their approach to service delivery.