The question raised in this study is: Why are similar companies so different? That is, why do companies of the same size, in the same line of business, and with the same organizational structures, etc., function in different ways? The answer to these questions is expected to be found through knowledge of basic ideas in companies. Important points of departure are that small companies are interesting research objects and that an organization can be viewed as a set of deep and surface structures which may appear in the language of its members and other interested parties. Based chiefly on deep interviews, the study is intended to generate knowledge and understanding of basic ideas and their function in small companies. The deep structures of the four companies show that the basic ideas can be understood as ideologies. They refer to basic values, are apprehended by the members of the organization and other interested parties, and prescribe what is desirable. The differences between the cases form the basis of a classification of the ideologies into four ideal types: capitalistic, religious, narcissistic, and socialistic. The surface structures are viewed in two perspectives, one referring to the behaviour of the companies and the other to the relational behaviour between the companies and the interested parties. The former shows that the patterns of behaviour are different in the four companies and may be characterized as efficiency-directed, adaptation-directed, ego-directed, and socially-directed. A comparison between these patterns of behaviour and the ideologies of the companies makes the directing function of the ideologies visible. Through situation interpretation, ideologies direct organizational behaviour towards particular patterns. The relational perspective causes the controlling function of ideologies to appear. Differences in co-acting between the companies - that is, the extent to which and on what grounds the interested parties behave in accordance with the behaviour of the companies and the attitudes of the interested parties to the ideological values - show that ideologies can exercise control either through their power over problem interpretation or their power over acting. The results of this study indicate that the answer to the initial question is that organizations have different ideological faces. / digitalisering@umu