This course provides an in-depth introduction to the theoretical foundations and contemporary developments in the sociology of organisations. It will address the main themes that have marked this field, such as the division of labour, rationality, power, leadership, change, the institution, the network, regulation, as well as organisational identity and cultures. Initially, we will review the classic concepts and approaches of organisational sociology, before focusing at greater length on the modern theories that permeate this field. The aim is to analyse organisational behaviour and structures, taking account of their internal dynamics and their environments, through the prism of different theoretical currents. To achieve this, we will rely on the reading of seminal texts as well as case studies in various socio-economic sectors (companies, administrations, associations), in order to gain a better understanding of organisational logics, their transformations and the issues that run through them.