Revision with unchanged content. This book explores design tools based on evolutionary computation (EC), oriented primarily toward conceptual design of architectural and civil engineering structures. EC tools are well suited for exploration in a way which promotes creative design. The multiplicity of solutions generated by EC techniques is less likely to cause design fixation, and so promote a more thorough exploration of possible solutions. The use of such tools also allows the designer greater latitude in exploring design criteria, such as aesthetics, by utilizing an interactive human-computer interface. This book begins with a survey of techniques that have been used in early phases of architectural design, and establishes a set of successful attributes, which are then discussed in the context of EC techniques. Finally, a specific implementation developed by the author is described. Several examples are given in the area of architectural engineering, and comparisons are made with results obtained with more conventional optimization tools. This book is especially useful for designers interested in new methods for generating and exploring structural form, and is accessible to non-programmers in either field.