The Second International Congress on Ambiances looks at a broad range of ambiances, including those of an architectural, urban, social, aesthetic, political, technical, environmental and pedagogical nature. Rather than seeking to formally define what ambiance means, we wish to look at ambiance in action and draw up a meaningful map of its uses. What processes are at work in the appearance and dynamics of an ambiance? How can we understand ambiances in terms of their impact and the outcomes they give rise to? In what ways do ambiances contribute to transformations of the built environment and the currently ongoing changes in urban areas? What type of performance does a given ambiance lend itself to? These proceedings provide a comprehensive coverage of the answers provided by the researchers, architects, town planners and artists who took part in the Second International Congress on Ambiances.