Component-based software emerged as a promising paradigm to deal with the ever increasing need for mastering systems' complexity, their evolution and reuse, and driving software engineering into sound production and engineering standards. Soon, however, it became a popular technology long before consensual definitions and principles, let alone formal foundations, have been put forward. Issues like mathematical models for components, their interaction and composition, or rigourous approaches to verification, deployment, testing and certification remain open research questions and challenging opportunities for formal methods. Moreover, new challenges are raised by applications to non conventional areas, such as safety-critical, mobile, and/or embedded systems. The objective of FACS'2005 is to bring together researchers in the areas of component software and formal methods to promote a deep understanding of this paradigm and its applications. The Workshop will also be interested in defining the common aspects of components and component-based development. It is expected that formal paper presentations be followed by lively debate in a stimulating atmosphere. Possible topics include, but are not limited to: * formal models for software components and component interaction * design and verification methods for component software * component composition and deployment: models, calculi, languages * component testing * specification of extra-functional properties in component software * certification of components and software architectures * component software vs object orientation * components for real-time, safety-critical, secure and/or embedded systems * experience reports and case studies in component software FACS'05 is the second in a series of workshops, founded by the International Institute for Software Technology of the United Nations University. The first FACS workshop was held in Pisa, Italy, in September 2003, collocated with FM'03.