The general objective of this dissertation was to enhance the understanding of organizational effectiveness by clarifying contingency theory. Key concepts, hypotheses, and models were explicated and selected contingency hypotheses were tested;Major accomplishments were made relative to clarifying contingency concepts. It was shown that the environment can be conceptualized in terms of two major components, the objective environmental suprasystem and the subjective environment. Subsystems of the organization were identified, with emphasis placed on clarifying the meanings of structural dimensions. Organizational effectiveness was defined in terms of the criteria of one internal organizational constituent, the administrators, and two external constituent groups, public representatives and clientele;Major contributions were provided toward clarifying contingency models. Generally, contingency models consist of those which pertain to either environmental or technological contingencies. Only the first group of contingency variants were given major consideration. Environmental contingency models were further differentiated in terms of traditional models which focus on the objective environment and contrasting variants which emphasize the subjective environment;Traditional contingency theory concentrated on resolving the Weberian-human relations argument. One traditional variant is the moderator model which treats objective environmental variables as moderators and examines the different effects of the moderators on relationships between structural and effectiveness variables. The second major variant is the consonance model. It consists of a general hypothesis which posits that organizations with structural characteristics consonant with their environmental characteristics will be more effective than organizations with dissonant environmental-structural configurations;Moderator and consonance hypotheses utilizing objective and subjective environmental concepts and three effectiveness criteria were tested. Also, relationships among environmental concepts were examined. Virtually no support was found for the contingency theory of organizational effectiveness.