This paper delves into organizational behaviour which is the study of how individuals and groups act within the organization. It explores the evolution of organizational behaviour from classical management theories, which emphasise structure, efficiency and control, to modern approaches that highlight human motivation, psychological factors and relationships. Key theoretical approaches include classical theory, human relations movement and Contemporary systems. The paper also articulates the role of motivation, personality and group dynamics in organizational effectiveness. The findings from the literature prove that there must exist a balance between technological advancements and human-focused practices to ensure long-term success.