In two remote northern provinces of the Lao People's Democratic Republic, provincial and district teams were trained and subsequently conducted a qualitative study using a participatory approach to investigate people's knowledge, attitudes, beliefs and practices in relation to women's and children's nutrition. Using focus group discussions, key informant interviews, and structured observation, the teams found that certain nutrition behaviours, including food taboos, may contribute to the high prevalence of child malnutrition and micronutrient deficiencies in these northern provinces. Ethnic groups gave details of nutrition-related beliefs and practices; the teams found that many of these are likely to be amenable to change through relatively low-cost nutrition promotion informed by these findings. In particular, barriers to exclusive breastfeeding, food taboos and hygiene behaviour could be addressed. The study also demonstrated that with appropriate training, supervision and support, local teams are able to plan and conduct a large-scale qualitative study.