Criticized classical theories for emphasis on structure. Key theorists: chester barnard, robert merton, herbert simon, philip selznick. Stressed instead the importance of co-operation in organizations group over the individual morality and leadership. Trained incapacity the actions based on training and skills which have been successful applied in the past may result in inappropriate responses under changed conditions. Esprit de corps bureaucrats defend own interests. Impersonality can lead to con icts with public/clientele. Work was a response to both fayol and gulick & urwick. Didn"t just criticize classical theory, he attacked it. No general principles of management inconsistent, con icting and inapplicable. Proverbs of administrations principles of management had equally plausible yet contradictory principle e. g. narrow span of control= e cient, but resulted in hierarchy (ine cient) Organizations are co-operative systems individuals interacting as wholes in relation to a formal system of co-ordination. Formal and informal aspects of an organization. Main contributions from the 1960s to the 1980s.