This work compares, analyzes and classifies the well-known theories of the firm. The analysis takes into account various positional, target, environmental and social aspects of firm’s activities. The analysis provides the directions along which the theory of the firm may develop. The work argues for a unified theory of the firm that should be complete, systemic and dynamic. These requirements should reflect the firm as a multifunctional and multistructural subject of the economic space. System-integrational theory of the enterprise that is developed by the author is being broadened by the inclusion of the eventual structure that facilitates the coherence of various subsystems and makes the theory more dynamic.