The Center for Complexity & Biosystems (CC&B) is a new interdisciplinary center for complex systems at the University of Milan. CC&B is subdivided in three thematic areas (Physics & Materials, Biosystems, Computer Science) which are all represented by the steering committee that also includes two external members. The center develops and has expertise in various quantitative analysis tools. The functioning of cellular processes, the organization of a biological organism, social dynamics and the behavior of many materials are complex phenomena emerging in a non trivial way from the interaction of an ensemble of elementary elements. To tackle the scientific and technological challenges posed by complex systems we need a new interdisciplinary approach that can help us to interpret the growing amount of data in all these fields of research. The CC&B is taking the challenge to study emergent properties of complex, biological and biomimetic materials, to understand how elementary cellular and bio-molecular processes result in the physiological and pathological behavior of an organism, and to analyze quantitatively dynamics of complex networks.