The 1977 book A Pattern Language was a landmark in the design world, introducing amethodology that has since become remarkably widespread and effective across manyfields. Among them is software, where "design patterns" have since become an industrystandard. Important spinoffs include peer-to-peer collaboration technologies like wiki— the basis of Wikipedia and related innovations — as well as Agile Methodology.Yet curiously, the one field where pattern methodology has lagged most conspicuouslyis the one where it began, the built environment. In part, the popular appeal of the1977 book served to "freeze" the initial set of patterns, greatly slowing further peer-to-peer development in environmental design — contrary to the original authors' statedaims. As one remedy, we present here — in one of many more hoped-for future com-panion volumes to the original classic book — a new collection of 80 patterns for anew era of urban challenges, including rapid urbanization, slum upgrading, sustainableurbanism, urban technologies, and new tools and strategies to meet these and otherchallenges.This new collection comes as a contribution to a five-year collaboration with UN-Hab-itat on implementation of the "New Urban Agenda," a framework document adoptedby consensus by all 193 countries of the United Nations. However, there remains anurgent need to implement its humane aspirations, using tools and strategies groundedin research evidence, but also subject to revision, addition and refinement with newfindings from new collaborators.This volume aims to meet that need — together with the launch of an online com-panion pattern "repository", available at npl.wiki. Both initiatives were developed incollaboration with Ward Cunningham, wiki inventor, and pioneer of pattern languagesof programming as well as Agile Methodology. Both are meant to expand the capacityof pattern languages in support of a hopeful new era of open-source, human-centered,life-enriching technology."The technology of "A Pattern Language' launched Wikipedia and the other programmingmethods we advanced. We are pleased to be a part of the cyber life of this work, returningagain to have an impact on the built world."- Ward Cunningham, inventor of wiki, and co-developer ofpattern languages of programming"The fact is, that we have written [the original] book as a first step in the society-wideprocess by which people will gradually become conscious of their own pattern languages,and work to improve them... we imagine this pattern language might be related to thecountless thousands of other languages we hope that people will make for themselves, inthe future..."— Christopher Alexander and co-authors,A Pattern Language (1977)