The workshop String and M theory approaches to particle physics and cosmology will cover the most active areas of modern String Theory. Including the implications on the physics of microscopic and macroscopic scales, like the particle physics in and beyond the Standard Model, and cosmological models of the early universe. Our current knowledge of the fundamental forces of physics is based on two well-established theories: the standard model of particle physics, and Einstein's general relativity. The standard model gives an impressively accurate description of the sub-atomic particles and their interactions. However, it cannot be viewed as a truly fundamental theory since it has many arbitrary parameters and ignores gravity, which is the most familiar force of all. On the other hand, general relativity gives a beautiful description of the large-scale gravitational forces within our universe. In particular, cosmological theories based on Einstein's theory explain very well many observed features of the universe. Particularly interesting is the recent observation that the universe is expanding due to the influence of ``dark energy'', whose simplest realization is Einstein's cosmological constant. However, general relativity is not a complete theory since it seems to be inconsistent with quantum principles, which are vital for explaining physics at sub-atomic distance scales. The apparent incompatibility of general relativity and quantum theory has been the central paradox of this area of theoretical physics for more than 75 years. Indeed, the search for an underlying theory that unifies all forces, including gravity, has been one of the main motivations for much of the research since the formulation of quantum theory in 1925. Important developments within the framework of conventional quantum field theory included the construction of grand unified theories and supergravity, but they failed to resolve the most basic inconsistencies. The framework of string theory is currently by far the most promising candidate for a consistent unified theory. It has a structure that differs radically from that of any quantum field theory although its basic premise is remarkably simple. Within string theory all of the different `fundamental' particles (the leptons, the quarks, the photon, .....) are identified with different vibration modes of a single string-like object. This not only gives a simple unified description of all the particles and their forces but also appears to avoid the long-standing conflicts between quantum theory and general relativity. One should keep in mind, however, that string theory is still an ongoing project. Many of its aspects, such as its non-perturbative formulation and its underlying defining principles, are only beginning to be understood. One of the main objectives in this area of research is to make quantitative connections between string theory and experimental physics on microscopic and macroscopic scales. One of the ultimate goals is to provide a model from which one could derive the observed low energy physics as its effective theory. We are still far from a solution to this problem, but recently new models have been devised that come close to the standard model in many respects. The main new ingredient is that these models contain D-branes and open strings in a consistent manner, and branes carry charges and fluxes that generate potentials. On the other hand, string theory is the leading candidate for the fundamental theory of gravitational interactions, recent successes on this area include detailed connections with the physics of black holes. It should also describe the cosmology of the early universe immediately after the big bang. This has become one of the central themes in string theory. The new tools that are being used for model building in high-energy physics are being actively applied also to modelling the early universe. In particular D-branes and fluxes that appear to stabilize the moduli fields of string theory may provide new mechanisms for the cosmological inflation. These investigations also build on another important set of ideas that has emerged in recent years: the gauge-gravity correspondence. This exact duality between gauge theories and strings provides a non-perturbative definition of string theory in certain backgrounds. It also gives us tools to investigate the properties of strongly coupled gauge theories by means of dual (super)gravity models. In particular, it provides new insights into various non-perturbative aspects of the standard model, like quark confinement and chiral symmetry breaking, which are currently under study with numerical simulations in the context of lattice gauge theory. One aspect of the rich structure of string theory is that it incorporates a very wide range of ideas from many areas of theoretical physics and modern mathematics. This makes it an exceptionally difficult subject to master since it requires a very broad range of expertise using a variety of techniques. Collaboration and frequent discussions are therefore essential, since the experts in any particular sub-area are often located in different institutions. This extended workshop with the participation of the leading experts on the field (see below a first list of interested physicists) will help to make progress in the field. During the workshop we plan to have regular seminars and discussions by the participants. During the first and last weeks of the workshop there will also be two 3-day conferences open to wider audience. We think that this set-up, together with the presence of world experts in the field, will provide also a natural environment to train PhD students and young researches, especially those coming from the Italian universities. The main topics to be discussed in the workshop are *** String compactifications and resulting low-energy theories *** Applications to string theory to Cosmology *** Dualities between gauge fields and strings *** Applications of topological strings The partial list of outstanding scientists who expressed interest in participation for at least a couple of weeks is (excluding the organizers): Costas Bachas, Eric Bergshoeff, Massimo Bianchi, Loriano Bonora, Gianguido Dall'Agata, Bernard de Wit, Frederik Denef, Paolo di Vecchia, Robbert Dijkgraaf, Michael Douglas, Roberto Emparan, Dan Freedman, Gary Gibbons, Mariana Graņa, Michael Green, Jeff Harvey, Chris Hull, Renata Kallosh, Nikita Nekrasov, Michela Petrini, Alexander Polyakov, Massimo Porrati, Eva Silverstein, Andy Strominger, Paul Townsend, Arkady Tseytlin, Gabriele Veneziano, Herman Verlinde, Alberto Zaffaroni.