Software architecture is a primary factor in the creation and evolution of virtually all products involving software. It is a topic of major interest in the research community where pronusmg formalisms, processes, and technologies are under development. Architecture is also of major interest in industry because it is recognized as a significant leverage point for manipulating such basic development factors as cost, quality, and interval. Its importance is attested to by the fact that there are several international workshop series as well as major conference sessions devoted to it. The First Working IFIP Conference on Software Architecture (WICSAl) provided a focused and dedicated forum for the international software architecture community to unify and coordinate its effort to advance the state of practice and research. WICSA 1 was organized to facilitate information exchange between practising software architects and software architecture researchers. The conference was held in San Antonio, Texas, USA, from February 22nd to February 24th, 1999; it was the initiating event for the new IFIP TC-2 Working Group on Software Architecture. This proceedings document contains the papers accepted for the conference. The papers in this volume comprise both experience reports and technical papers. The proceedings reflect the structure of the conference and are divided into six sections corresponding to the working groups established for the conference.