This paper discusses some of the recent developments in hygiene behaviour research, focusing on operational research. A series of "rapid' assessments of hygiene behaviour were carried out in Kenya, Tanzania and Ethiopia with a view to preparing a field handbook entitled Hygiene Evaluation Procedures (HEP). The HEP handbook is intended primarily for field personnel in water supply, sanitation and health/hygiene education projects who want to design and conduct their own systematic assessments of hygiene behaviour in their localities. The short studies provided useful practical insights into the concerns and needs of project staff for whom research allowances (human, material and time resources) are often very limited. In this paper emphasis is placed on both methodological and heuristic developments as the two are inseparable. It is suggested that in the domestic sphere, hygiene behaviour with respect to the disposal of children's faeces and domestic water use are two of the key areas that remain of universal relevance to water/sanitation related interventions. These can be assessed rapidly and effectively by using two indicators: means of disposal of children's faeces and handwashing at 'critical' times--after defaecation, after handling and/or disposing of children's faeces, before handling food and before feeding young children and eating. Appropriate combinations of anthropological methods and participatory tools for measuring these indicators are described. The practical relevance of the resulting data for project design and implementation is highlighted.