Studies about geographical information systems (GIS) use contribute to geographic information science through critical evaluation of the concepts embedded in GIS tools. Social-behavioural studies about group use of GIS help us to understand the social implications of GIS because groups are fundamental units underlying intra-organizational, organization-wide, and inter-organizational activity in society. When group communication technology is integrated with basic GIS capabilities an enhanced version of GIS called 'participatory GIS' (PGIS) is created. Group use of PGIS technology can be studied by sampling social-behavioural events during human-computer-human interaction. Social-behavioural research about PGIS use requires an informed balance among three research domains--substantive, theoretical, and methodological--if we are to make balanced progress in participatory geographical information science associated with the critical evaluation of GIS use. In this paper, we draw from our research on GIS-supported collaborative decision making about land use and resource planning and a conceptual framework called Enhanced Adaptive Structuration Theory. We develop a new framework for understanding choices among data-gathering strategies for social-behavioural studies about PGIS use. The framework for data-gathering strategies is composed of two dimensions. One dimension is the level of induced control in social-behavioural relations during GIS use in a research setting. The other is the amount of pre- or post-structuring of variables embedded in data-collection techniques. Several common datagathering strategies, e.g. laboratory experiment, field experiment, case study, and field survey, are differentiated in terms of those dimensions. Objectives for empirical research are used to compare and contrast the data-gathering strategies. This framework helps researchers understand the trade-offs among various data-gathering strategies as the core of research designs for critical evaluations of PGIS use.