In cognitive ergonomics, laboratory experimentation using computer-based simulations (microworlds) has played a significant role in understanding human decision making and reasoning. In this paper, we describe the design and deployment of a social work microworld (BRIGIT), which simulates the electronic recording systems now widely implemented in UK children's services. BRIGIT provides a fabricated but realistic social work environment, enabling the fine structure of professional information processing to be studied in response to experimental manipulations, such as time pressure, etc. A preliminary experiment is described here, which shows BRIGIT to provide a convincing psychological experience and a useful research tool. As well as demonstrating its face and external validity, the results highlight BRIGIT's utility as a way of probing ‘practice culture’ and for examining different patterns of professional sense making. We conclude that the microworld paradigm provides a valuable and innovative approach for researching social work practice. A range of possible applications are discussed, not only in fundamental research, but as a practical tool for use in the workplace, such as for supporting staff selection. There is also obvious potential for ‘design research’ aimed directly at improving the usability and effectiveness of electronic systems, which is important given the widely reported problems of current ICT systems in social work.