The quest for measurement in health care paved the way for the myth of scale, which ultimately assumes that higher dimensions are associated with better organizational performance. Moreover, it pretends that organizational design is a simple issues, which could be dealt with through reductionism (Gharajedaghi, 1999). Organizations are conceived as engines (Morgan, 1986): human resources are easily replaceable and performance are predictable (Thietart, Forgues, 1995). This approach produces a veil of ignorance, which impoverishes the meaningfulness of organizational science. Sticking to it, several scholars have found that organizational dimensions are able to affect organizational performance in terms of efficiency (Chadwick, Hunter & Walston, 2004), effectiveness (Sahin & Ozcan, 2000), and adoption of innovative technologies (Irwin, Hoffman & Geiger, 1998). However, this reductionist reasoning does not catch the real nature of health care organizations. In fact, three sources of complexity affect the design and the functioning of health care organizations: 1) macro (scenario) sources: changes of social, demographic, and epidemiologic determinants generates momentous drawbacks on health needs, which inspire the work of health care organizations (Borgonovi, 2008); 2) meso (context) sources: health care organizations show deep interdependencies with the other entities operating in social care and public health, sharing responsibilities and liabilities with them (Borgonovi, 2007); 3) micro (organizational) sources: health care professionals are related each other by weak ties, cooperating to achieve an increased ability to meet the health needs of the population served (responsiveness); at the same time, they strive to maintain their own distinctiveness (Orton, Weick, 1990). The complexity perspective encourages to reconceptualise the idea of performance in the health sector. Anderson’s article “More is different” (1972) is the manifesto of the complexity revolution against reductionism. “A complex system is not merely constituted by the sum of its components, but by the intricate relationships between these components. In ‘cutting up’ a system, the analytical method destroys what it seeks to understand” (Cilliers, 1998, p. 2). From this point of view, health care organizations should be conceived as brains rather than engines. This metaphor suggests that health care organizations should be dealt with as organic, dynamic, living, and social systems (Capra, 2002), where the human and the technology dimensions interact.