WCOP 2001, held in conjunction with ECOOP 2001 in Budapest, Hungary, was the sixth workshop in the successful series of workshops on component-oriented programming. The previous workshops were held in conjunction with the respective ECOOP conferences in Linz, Austria; Jyväskylä, Finland; Brussels, Belgium; Lisbon, Portugal; and Sophia Antipolis, France. WCOP’96 had focussed on the principal idea of software components and worked towards definitions of terms. In particular, a high-level definition of what a software component is was formulated. WCOP’97 concentrated on compositional aspects, architecture and gluing, substitutability, interface evolution, and non-functional requirements. WCOP’98 had a closer look at issues arising in industrial practice and developed a major focus on the issues of adaptation. WCOP’99 moved on to address issues of component frameworks, structured architecture, and some bigger systems built using components frameworks. WCOP 2000 focussed on component composition, validation and refinement and the use of component technology in the software industry. This latest instance, WCOP 2001, continued the move from the basics to the hard problems that arise when applying component technology, including problem sets that overlap with other view points, such as aspectual separation of concerns.