This paper is about the application of professional information design practices that have grown out of research conducted by the Communication Research Institute (CRI), formerly the Communication Research Institute of Australia (CRIA), and others. In particular, it focuses on the role of testing in studio practice. Starting in the mid 1980s, CRI undertook a number of large-scale applied projects funded by government and industry to improve the quality of communication between large organisations and the public. The research focused on discovering the best methods for designing information for public use. The CRI research was able to draw on a substantial body of prior research in design methods (e.g. Jones 1970), document designs (e.g. Felker et al 1980) and specifically in information design (e.g. Easterby & Zwaga 1984). Moreover, a growing number of significant case histories published in this journal have provided an emerging view of professional practice in the field (e.g. Goodwin 1984, Tomaselli & Tomaselli 1984, Waller 1984) This early work suggests the possibility of a unified set of highly productive information design methods, and was foreshadowed in the important contributions of Pat Wright (e.g. Wright 1979). The work started at CRI in the mid-1980s focused on unifying information design methods and demonstrating their productivity (Fisher and Sless 1990). By 1992, it was possible to suggest that the resulting design methods had a wide general application to information design (Sless 1992). However, it remained to demonstrate that these methods could be applied consistently across a range of information design problems and that the resultant designs could consistently perform at an acceptable level. This paper reports on that demonstration. In particular it shows through practical examples how testing and measurement of a design’s performance has become an integral part of professional information design practice.