Book excerpt: This book presents a collection of revised refereed papers selected from the contributions to the Fifth International Workshop on Computer Aided Systems Theory, EUROCAST '95, held in Innsbruck, Austria in May 1995. The 42 full papers contained have been contributed by CAST theoreticians, tool-makers, designers, and appliers and reflect the full spectrum of activities in the area. The papers are organized in sections on systems theory, design environments, complex systems design, and specific applications.